What is the sequential progression of ECG changes as Serum Potassium rises in Hyperkalemia (K+ > 5.0 mEq/L)?

1) Mild-moderate (5.5–6.5 mEq/L): tall, narrow, symmetrically peaked ('tented') T waves; 2) Moderate-severe (6.5–7.5 mEq/L): prolonged PR interval, flattened/absent P waves, and widening of the QRS complex; 3) Severe (> 7.5–8.0 mEq/L): fusion of widened QRS and T wave into a 'sine-wave' pattern, degenerating into ventricular fibrillation or asystole.

What are the primary etiologies of Hypernatremia (Na+ > 145 mEq/L), and why should chronic hypernatremia also be corrected gradually (<= 10 mEq/L per 24 hours)?

Caused by unreplaced free water loss (insensible sweat/fever, osmotic diarrhea, Central or Nephrogenic Diabetes Insipidus) in patients without access to water (infants, intubated, elderly); rapid lowering of serum osmolality drives free water into hyperosmolar brain cells (which accumulated organic osmolytes), causing fatal Cerebral Edema and seizures.

What are the normal adult serum reference ranges for Sodium (Na+), Potassium (K+), Chloride (Cl-), and Bicarbonate (HCO3-)?

Sodium (Na+): 135–145 mEq/L; Potassium (K+): 3.5–5.0 mEq/L; Chloride (Cl-): 96–106 mEq/L; Serum Bicarbonate (total CO2/HCO3-): 22–28 mEq/L.

What is the diagnostic significance of each type of Urinary Cast found on microscopic urine sediment analysis (Hyaline, RBC, WBC, Muddy Brown Granular, Waxy, Fatty)?

Hyaline casts: normal Tamm-Horsfall mucoprotein (exercise, dehydration, diuretics); RBC casts (and dysmorphic RBCs): Glomerulonephritis (nephritic syndrome) or vasculitis; WBC casts: Acute Pyelonephritis or Acute Interstitial Nephritis (AIN); Muddy brown granular casts: Acute Tubular Necrosis (ATN); Broad waxy casts: advanced Chronic Kidney Disease / ESRD (dilated atrophic tubules); Fatty casts ('Maltese cross' oval fat bodies): Nephrotic Syndrome.

Why does Chronic Kidney Disease cause Secondary Hyperparathyroidism and Renal Osteodystrophy?

Failing kidneys cannot excrete phosphate (causing hyperphosphatemia, which binds free serum Ca2+) and lack functional proximal tubular 1-alpha-hydroxylase to convert 25-OH vitamin D into active 1,25-(OH)2 vitamin D (calcitriol); the resulting hypocalcemia and hyperphosphatemia chronically stimulate the parathyroid glands to secrete excess PTH, resorbing calcium from bone.

What is Microalbuminuria (moderately increased albuminuria), what is its reference range on a spot Urine Albumin-to-Creatinine Ratio (UACR), and why is it screened annually in diabetes?

A spot UACR of 30–300 mg/g (normal is 300 mg/g); it is the earliest clinical marker of incipient diabetic glomerulosclerosis, which is NOT detected by standard urine dipsticks (which only turn positive at > 300 mg/day) and prompts initiation of an ACE inhibitor or ARB (plus SGLT2 inhibitor) to slow CKD progression.

What are the normal reference ranges for routine Urinalysis (Specific Gravity, pH, Protein, Glucose, Ketones, RBCs, WBCs)?

Urine Specific Gravity: 1.005–1.030 (1.010 is isosthenuric with plasma); Urine pH: 4.5–8.0 (average ~6.0); Protein, Glucose, Ketones, Bilirubin, Nitrites, Leukocyte Esterase: Negative; Microscopic RBCs: <= 2/HPF; Microscopic WBCs: <= 2–5/HPF.

How do Leukocyte Esterase and Nitrites on a urine dipstick aid in diagnosing a Urinary Tract Infection (UTI)?

Leukocyte esterase is an enzyme released by lysed neutrophils (indicating pyuria / inflammation), whereas positive Nitrites indicate the presence of Gram-negative Enterobacterales (such as E. coli, Klebsiella, Proteus) that reduce dietary urinary nitrates to nitrites (Note: Gram-positive Enterococcus and Staphylococcus saprophyticus do not reduce nitrates).

What do a low Urine Specific Gravity ( 1.030) indicate?

Low specific gravity ( 1.030) indicates concentrated urine (dehydration, hypovolemia, SIADH, heart failure) or presence of heavy solutes (glycosuria, proteinuria, IV radiocontrast dye).

Aside from prerenal dehydration/hypoperfusion, what non-renal clinical conditions elevate the BUN-to-Creatinine ratio above 20:1?

Upper gastrointestinal bleeding (digestion and absorption of hemoglobin blood proteins in the gut), high-protein diets or total parenteral nutrition (TPN), hypercatabolic states (burns, sepsis, high-dose systemic corticosteroids), and tetracycline use.

How do you classify Hypotonic Hyponatremia (< 135 mEq/L, Posm < 280 mOsm/kg) by volume status (Hypovolemic, Euvolemic, Hypervolemic) and Urine Sodium (UNa)?

Hypovolemic: UNa 20 mEq/L (thiazide/loop diuretics, adrenal insufficiency, cerebral salt wasting); Euvolemic (UNa > 20 mEq/L, Uosm > 100): SIADH, hypothyroidism, glucocorticoid deficiency, psychogenic polydipsia (Uosm 20).

What are the two most common causes of Hypercalcemia (accounting for > 90% of cases), and what is the first-line acute treatment for severe hypercalcemic crisis?

Primary Hyperparathyroidism (most common in outpatients; high PTH) and Malignancy (most common in hospitalized patients; PTHrP secretion by squamous cell lung/renal/breast cancer or osteolytic bone metastases/multiple myeloma; suppressed PTH); first-line acute treatment is aggressive IV 0.9% Normal Saline hydration (4–6 L/day to restore GFR and promote calciuria) followed by IV bisphosphonates (zoledronic acid, pamidronate) and calcitonin.

What are the critical nursing safety rules when administering Intravenous Potassium Chloride (KCl) for hypokalemia?

1) NEVER administer IV KCl by IV push or bolus (causes fatal cardiac arrest); 2) Always dilute and infuse via an infusion pump at = 0.5 mL/kg/hr); and 4) Check and correct concurrent hypomagnesemia (refractory hypokalemia cannot be corrected until Mg2+ is repleted).

What are the classic clinical and ECG manifestations of Hypokalemia (K+ < 3.5 mEq/L)?

Clinical: skeletal muscle weakness, cramps, hyporeflexia, paralytic ileus, and digoxin toxicity predisposition; ECG progression: flattened or inverted T waves, ST-segment depression, and prominent U waves (after the T wave), with risk of prolonged QT and Torsades de Pointes.

What is the three-step emergency pharmacological management of severe Hyperkalemia with ECG changes?

Step 1 — Stabilize cardiac myocyte membrane immediately (within 1–3 min, does NOT lower serum K+): IV Calcium Gluconate (or Calcium Chloride via central line); Step 2 — Shift K+ intracellularly (within 15–30 min): IV Regular Insulin (10 units) + Dextrose (D50W, 25–50 g), nebulized high-dose Albuterol (beta-2 agonist), and IV Sodium Bicarbonate (if metabolic acidosis present); Step 3 — Eliminate K+ from the body: loop diuretics (furosemide), selective GI potassium binders (sodium zirconium cyclosilicate [Lokelma] or patiromer [Veltassa]; avoid sodium polystyrene sulfonate [Kayexalate] in post-op/ileus patients due to intestinal necrosis risk), or emergent Hemodialysis.

What is Pseudohyponatremia versus Hypertonic (Translocational) Hyponatremia, and how is Measured Serum Sodium corrected for severe hyperglycemia?

Pseudohyponatremia is a laboratory artifact from extreme hypertriglyceridemia or paraproteinemia (normal serum osmolality); Hypertonic hyponatremia occurs when extracellular glucose draws water out of cells, diluting serum Na+ by ~1.6 mEq/L (up to 2.4 mEq/L when glucose > 400 mg/dL) for every 100 mg/dL rise in plasma glucose above 100 mg/dL.

How do the BUN-to-Creatinine Ratio, Urine Osmolality, Urine Sodium (UNa), and Fractional Excretion of Sodium (FENa) distinguish Prerenal Azotemia from Intrinsic Acute Tubular Necrosis (ATN)?

Prerenal AKI (renal hypoperfusion with intact tubular function avidly reabsorbing Na+ and urea): BUN:Cr ratio > 20:1, Urine Osmolality > 500 mOsm/kg, Urine Na+ 40 mEq/L, and FENa > 2%.

What are the clinical manifestations of Hypomagnesemia ( 2.5 mEq/L), and what is the antidote for Magnesium toxicity?

Hypomagnesemia (alcoholism, loop/thiazide diuretics, PPIs, diarrhea): hyperreflexia, tremors, tetany, refractory hypokalemia/hypocalcemia, and Torsades de Pointes (polymorphic VT); Hypermagnesemia (renal failure or excessive IV MgSO4 in preeclampsia): sequential loss of deep tendon reflexes (patellar reflex lost at > 4 mEq/L), lethargy, hypotension/bradycardia, respiratory depression (> 10 mEq/L), and cardiac arrest -> immediate antidote is IV Calcium Gluconate.

What are the nursing care priorities for an Arteriovenous Fistula (AVF) or Graft in a hemodialysis patient?

Assess patency every shift by palpating for a continuous 'thrill' (vibration) and auscultating for a 'bruit' (whooshing sound); NEVER take blood pressures, perform venipuncture, start IV lines, or apply tight tourniquets/restraints on the extremity with the AV access.

Why do Serum Calcium and Serum Phosphate have an inverse relationship in parathyroid disorders, and what life-threatening syndrome causes acute severe Hypophosphatemia (< 1.0 mg/dL)?

Parathyroid hormone (PTH) increases renal calcium reabsorption while inhibiting proximal tubular phosphate reabsorption (phosphaturia), keeping the Ca × PO4 solubility product constant; acute severe Hypophosphatemia (along with hypokalemia and hypomagnesemia) is the hallmark of Refeeding Syndrome when carbohydrates/insulin are reintroduced to a chronically malnourished or alcoholic patient, depleting ATP and 2,3-BPG and causing respiratory muscle failure, rhabdomyolysis, and hemolysis.

On a urine dipstick, what does a positive 'Heme / Blood' reaction with ZERO red blood cells seen on microscopic examination signify?

Either Myoglobinuria (from Rhabdomyolysis — skeletal muscle breakdown with markedly elevated serum Creatine Kinase > 5,000–10,000 U/L and hyperkalemia) OR Hemoglobinuria (from intravascular hemolysis with low haptoglobin and elevated LDH).

What is the 'AEIOU' mnemonic for the emergent indications for Hemodialysis in Acute Kidney Injury or CKD?

A — Acidosis (severe refractory metabolic acidosis, pH 6.5 mEq/L or rapidly rising); I — Intoxications (dialyzable toxins: Lithium, Methanol, Ethylene glycol, Salicylates, Valproate, Isopropanol); O — Overload (diuretic-refractory fluid overload / pulmonary edema); U — Uremia (uremic pericarditis/tamponade, uremic encephalopathy/seizures, uremic bleeding).

What are the six KDIGO stages of Chronic Kidney Disease (CKD) based on eGFR (G1 to G5)?

G1: eGFR >= 90 mL/min/1.73 m² (with albuminuria/structural kidney damage); G2: eGFR 60–89 (mildly decreased); G3a: eGFR 45–59 (mild-to-moderate); G3b: eGFR 30–44 (moderate-to-severe); G4: eGFR 15–29 (severe reduction, prepare for renal replacement); G5: eGFR < 15 mL/min/1.73 m² or dialysis (Kidney Failure / ESRD).

Why must iodinated IV contrast media and Metformin be managed carefully in patients with impaired renal function (eGFR < 30–60 mL/min/1.73 m²)?

Iodinated contrast can cause Contrast-Induced Nephropathy (CIN; prevented by pre- and post-procedure isotonic IV 0.9% NaCl hydration and holding nephrotoxins like NSAIDs); Metformin is excreted unchanged by the kidneys and is contraindicated when eGFR < 30 mL/min/1.73 m² (and held at the time of iodinated contrast if eGFR 30–60) because renal accumulation precipitates fatal Metformin-Associated Lactic Acidosis (MALA).

What are the clinical manifestations and ECG findings of Hypocalcemia (Total Ca 10.5 mg/dL)?

Hypocalcemia: neuromuscular hyperexcitability, perioral/acral paresthesias, muscle cramps, laryngospasm, seizures, positive Chvostek and Trousseau signs, and PROLONGED QT interval on ECG; Hypercalcemia ('stones, bones, abdominal groans, thrones, and psychiatric overtones'): nephrolithiasis, bone pain, constipation/pancreatitis, polyuria (nephrogenic DI), lethargy/confusion, muscle weakness/hyporeflexia, and SHORTENED QT interval on ECG.

How does acute acidemia versus alkalemia alter free Ionized Calcium levels without changing Total Serum Calcium?

In alkalemia (e.g., respiratory alkalosis from hyperventilation), fewer H+ ions compete for negatively charged binding sites on albumin, increasing calcium-albumin binding and LOWERING free ionized calcium (triggering perioral numbness and carpopedal tetany); acidemia displaces Ca2+ from albumin, raising ionized calcium.

What are the normal adult serum reference ranges for Total Calcium (Ca2+), Ionized Calcium, Magnesium (Mg2+), and Phosphate (PO4-)?

Total Calcium: 8.5–10.5 mg/dL (9.0–10.5 mg/dL); Ionized Calcium: 4.5–5.6 mg/dL (1.12–1.40 mmol/L); Magnesium: 1.5–2.5 mEq/L (1.8–2.6 mg/dL); Inorganic Phosphate: 2.5–4.5 mg/dL.

How do you clinically and biochemically distinguish Nephrotic Syndrome from Nephritic Syndrome?

Nephrotic syndrome (podocyte foot-process damage: Minimal Change, FSGS, Membranous, Diabetic/Amyloid): massive proteinuria (> 3.5 g/24 hr or urine protein:Cr ratio > 3.5), hypoalbuminemia (< 3.0 g/dL), generalized pitting edema, hyperlipidemia/fatty casts, and hypercoagulability (loss of antithrombin III in urine); Nephritic syndrome (GBM inflammation: Post-streptococcal, IgA nephropathy, Lupus, RPGN): hematuria with acanthocytes/RBC casts, hypertension, oliguria/azotemia, and mild-to-moderate proteinuria (< 3.5 g/day).

What is the maximum safe rate of serum sodium correction in chronic hyponatremia, and what catastrophic complication occurs if corrected too rapidly?

Do not exceed a rise of 8 mEq/L (or 6–8 mEq/L in high-risk patients; absolute max 10–12 mEq/L) in any 24-hour period; overly rapid correction causes Osmotic Demyelination Syndrome (Central Pontine Myelinolysis), resulting in irreversible quadriplegia, pseudobulbar palsy, and 'locked-in' syndrome.

What are the normal adult reference ranges for Blood Urea Nitrogen (BUN), Serum Creatinine (Cr), and estimated Glomerular Filtration Rate (eGFR)?

BUN: 7–20 mg/dL (8–21 mg/dL); Serum Creatinine: 0.6–1.2 mg/dL (0.5–1.1 mg/dL in females, 0.7–1.3 mg/dL in males); Normal eGFR (calculated via the race-free 2021 CKD-EPI creatinine or combined creatinine-cystatin C equation): >= 90 mL/min/1.73 m² (with CKD defined as eGFR = 30 mg/g persisting for >= 3 months).

How do you calculate Corrected Serum Calcium in a patient with hypoalbuminemia, and why does low albumin affect total calcium without changing ionized calcium?

Corrected Ca (mg/dL) = Measured Total Ca + 0.8 × (4.0 - Serum Albumin in g/dL); because ~40% of serum calcium is bound to albumin, hypoalbuminemia lowers total serum calcium while physiologically active free ionized calcium remains normal.

When is 3% Hypertonic Saline indicated in hyponatremia, and how is Syndrome of Inappropriate ADH (SIADH) managed?

3% hypertonic saline (100 mL IV bolus over 10 min) is reserved for acute symptomatic hyponatremia with severe neurological manifestations (seizures, coma, herniation) to acutely raise Na+ by 4–6 mEq/L; chronic euvolemic SIADH is managed with free water restriction, oral salt tablets + loop diuretics, urea, or vasopressin V2-receptor antagonists (tolvaptan, conivaptan).

Serum Electrolytes (Na+, K+, Ca2+, Mg2+, PO4-, Cl-) & Renal Panel (BUN, Creatinine, eGFR, Urinalysis)

NCLEX adult reference ranges and clinical interpretation for serum electrolytes (Na+, K+, Ca2+, Mg2+, PO4-, Cl-), hyponatremia/hypernatremia, hypokalemia/hyperkalemia ECG progressions and IV KCl safety, renal panel (BUN, creatinine, eGFR, FENa), CKD stages, hemodialysis indications, and urinalysis casts.

Level: basic
Languages: en → en
Cards: 32
Markdown: Serum Electrolytes (Na+, K+, Ca2+, Mg2+, PO4-, Cl-) & Renal Panel (BUN, Creatinine, eGFR, Urinalysis) (.md)

Flashcards (32)

#	Front (Term / Question)	Back (Definition / Answer)
1	What is the sequential progression of ECG changes as Serum Potassium rises in Hyperkalemia (K+ > 5.0 mEq/L)?	1) Mild-moderate (5.5–6.5 mEq/L): tall, narrow, symmetrically peaked ('tented') T waves; 2) Moderate-severe (6.5–7.5 mEq/L): prolonged PR interval, flattened/absent P waves, and widening of the QRS complex; 3) Severe (> 7.5–8.0 mEq/L): fusion of widened QRS and T wave into a 'sine-wave' pattern, degenerating into ventricular fibrillation or asystole.
2	What are the primary etiologies of Hypernatremia (Na+ > 145 mEq/L), and why should chronic hypernatremia also be corrected gradually (<= 10 mEq/L per 24 hours)?	Caused by unreplaced free water loss (insensible sweat/fever, osmotic diarrhea, Central or Nephrogenic Diabetes Insipidus) in patients without access to water (infants, intubated, elderly); rapid lowering of serum osmolality drives free water into hyperosmolar brain cells (which accumulated organic osmolytes), causing fatal Cerebral Edema and seizures.
3	What are the normal adult serum reference ranges for Sodium (Na+), Potassium (K+), Chloride (Cl-), and Bicarbonate (HCO3-)?	Sodium (Na+): 135–145 mEq/L; Potassium (K+): 3.5–5.0 mEq/L; Chloride (Cl-): 96–106 mEq/L; Serum Bicarbonate (total CO2/HCO3-): 22–28 mEq/L.
4	What is the diagnostic significance of each type of Urinary Cast found on microscopic urine sediment analysis (Hyaline, RBC, WBC, Muddy Brown Granular, Waxy, Fatty)?	Hyaline casts: normal Tamm-Horsfall mucoprotein (exercise, dehydration, diuretics); RBC casts (and dysmorphic RBCs): Glomerulonephritis (nephritic syndrome) or vasculitis; WBC casts: Acute Pyelonephritis or Acute Interstitial Nephritis (AIN); Muddy brown granular casts: Acute Tubular Necrosis (ATN); Broad waxy casts: advanced Chronic Kidney Disease / ESRD (dilated atrophic tubules); Fatty casts ('Maltese cross' oval fat bodies): Nephrotic Syndrome.
5	Why does Chronic Kidney Disease cause Secondary Hyperparathyroidism and Renal Osteodystrophy?	Failing kidneys cannot excrete phosphate (causing hyperphosphatemia, which binds free serum Ca2+) and lack functional proximal tubular 1-alpha-hydroxylase to convert 25-OH vitamin D into active 1,25-(OH)2 vitamin D (calcitriol); the resulting hypocalcemia and hyperphosphatemia chronically stimulate the parathyroid glands to secrete excess PTH, resorbing calcium from bone.
6	What is Microalbuminuria (moderately increased albuminuria), what is its reference range on a spot Urine Albumin-to-Creatinine Ratio (UACR), and why is it screened annually in diabetes?	A spot UACR of 30–300 mg/g (normal is < 30 mg/g; macroalbuminuria/overt nephropathy is > 300 mg/g); it is the earliest clinical marker of incipient diabetic glomerulosclerosis, which is NOT detected by standard urine dipsticks (which only turn positive at > 300 mg/day) and prompts initiation of an ACE inhibitor or ARB (plus SGLT2 inhibitor) to slow CKD progression.
7	What are the normal reference ranges for routine Urinalysis (Specific Gravity, pH, Protein, Glucose, Ketones, RBCs, WBCs)?	Urine Specific Gravity: 1.005–1.030 (1.010 is isosthenuric with plasma); Urine pH: 4.5–8.0 (average ~6.0); Protein, Glucose, Ketones, Bilirubin, Nitrites, Leukocyte Esterase: Negative; Microscopic RBCs: <= 2/HPF; Microscopic WBCs: <= 2–5/HPF.
8	How do Leukocyte Esterase and Nitrites on a urine dipstick aid in diagnosing a Urinary Tract Infection (UTI)?	Leukocyte esterase is an enzyme released by lysed neutrophils (indicating pyuria / inflammation), whereas positive Nitrites indicate the presence of Gram-negative Enterobacterales (such as E. coli, Klebsiella, Proteus) that reduce dietary urinary nitrates to nitrites (Note: Gram-positive Enterococcus and Staphylococcus saprophyticus do not reduce nitrates).
9	What do a low Urine Specific Gravity (< 1.005) versus an elevated Urine Specific Gravity (> 1.030) indicate?	Low specific gravity (< 1.005) indicates maximally dilute urine (Diabetes Insipidus, psychogenic polydipsia, or excess IV hypotonic fluid therapy); High specific gravity (> 1.030) indicates concentrated urine (dehydration, hypovolemia, SIADH, heart failure) or presence of heavy solutes (glycosuria, proteinuria, IV radiocontrast dye).
10	Aside from prerenal dehydration/hypoperfusion, what non-renal clinical conditions elevate the BUN-to-Creatinine ratio above 20:1?	Upper gastrointestinal bleeding (digestion and absorption of hemoglobin blood proteins in the gut), high-protein diets or total parenteral nutrition (TPN), hypercatabolic states (burns, sepsis, high-dose systemic corticosteroids), and tetracycline use.
11	How do you classify Hypotonic Hyponatremia (< 135 mEq/L, Posm < 280 mOsm/kg) by volume status (Hypovolemic, Euvolemic, Hypervolemic) and Urine Sodium (UNa)?	Hypovolemic: UNa < 20 mEq/L (GI losses, burns, third-spacing) vs. UNa > 20 mEq/L (thiazide/loop diuretics, adrenal insufficiency, cerebral salt wasting); Euvolemic (UNa > 20 mEq/L, Uosm > 100): SIADH, hypothyroidism, glucocorticoid deficiency, psychogenic polydipsia (Uosm < 100); Hypervolemic (UNa < 20 mEq/L): CHF, cirrhosis, nephrotic syndrome (or CKD/AKI with UNa > 20).
12	What are the two most common causes of Hypercalcemia (accounting for > 90% of cases), and what is the first-line acute treatment for severe hypercalcemic crisis?	Primary Hyperparathyroidism (most common in outpatients; high PTH) and Malignancy (most common in hospitalized patients; PTHrP secretion by squamous cell lung/renal/breast cancer or osteolytic bone metastases/multiple myeloma; suppressed PTH); first-line acute treatment is aggressive IV 0.9% Normal Saline hydration (4–6 L/day to restore GFR and promote calciuria) followed by IV bisphosphonates (zoledronic acid, pamidronate) and calcitonin.
13	What are the critical nursing safety rules when administering Intravenous Potassium Chloride (KCl) for hypokalemia?	1) NEVER administer IV KCl by IV push or bolus (causes fatal cardiac arrest); 2) Always dilute and infuse via an infusion pump at <= 10 mEq/hr via a peripheral vein (up to 20 mEq/hr via a central line with continuous ECG monitoring); 3) Verify adequate urine output (>= 0.5 mL/kg/hr); and 4) Check and correct concurrent hypomagnesemia (refractory hypokalemia cannot be corrected until Mg2+ is repleted).
14	What are the classic clinical and ECG manifestations of Hypokalemia (K+ < 3.5 mEq/L)?	Clinical: skeletal muscle weakness, cramps, hyporeflexia, paralytic ileus, and digoxin toxicity predisposition; ECG progression: flattened or inverted T waves, ST-segment depression, and prominent U waves (after the T wave), with risk of prolonged QT and Torsades de Pointes.
15	What is the three-step emergency pharmacological management of severe Hyperkalemia with ECG changes?	Step 1 — Stabilize cardiac myocyte membrane immediately (within 1–3 min, does NOT lower serum K+): IV Calcium Gluconate (or Calcium Chloride via central line); Step 2 — Shift K+ intracellularly (within 15–30 min): IV Regular Insulin (10 units) + Dextrose (D50W, 25–50 g), nebulized high-dose Albuterol (beta-2 agonist), and IV Sodium Bicarbonate (if metabolic acidosis present); Step 3 — Eliminate K+ from the body: loop diuretics (furosemide), selective GI potassium binders (sodium zirconium cyclosilicate [Lokelma] or patiromer [Veltassa]; avoid sodium polystyrene sulfonate [Kayexalate] in post-op/ileus patients due to intestinal necrosis risk), or emergent Hemodialysis.
16	What is Pseudohyponatremia versus Hypertonic (Translocational) Hyponatremia, and how is Measured Serum Sodium corrected for severe hyperglycemia?	Pseudohyponatremia is a laboratory artifact from extreme hypertriglyceridemia or paraproteinemia (normal serum osmolality); Hypertonic hyponatremia occurs when extracellular glucose draws water out of cells, diluting serum Na+ by ~1.6 mEq/L (up to 2.4 mEq/L when glucose > 400 mg/dL) for every 100 mg/dL rise in plasma glucose above 100 mg/dL.
17	How do the BUN-to-Creatinine Ratio, Urine Osmolality, Urine Sodium (UNa), and Fractional Excretion of Sodium (FENa) distinguish Prerenal Azotemia from Intrinsic Acute Tubular Necrosis (ATN)?	Prerenal AKI (renal hypoperfusion with intact tubular function avidly reabsorbing Na+ and urea): BUN:Cr ratio > 20:1, Urine Osmolality > 500 mOsm/kg, Urine Na+ < 20 mEq/L, and FENa < 1% (FEUrea < 35% if on diuretics); Intrinsic ATN (necrotic tubular epithelium unable to concentrate urine or retain Na+): BUN:Cr ratio 10–15:1, Urine Osmolality < 350 mOsm/kg (isosthenuria), Urine Na+ > 40 mEq/L, and FENa > 2%.
18	What are the clinical manifestations of Hypomagnesemia (< 1.5 mEq/L) versus Hypermagnesemia (> 2.5 mEq/L), and what is the antidote for Magnesium toxicity?	Hypomagnesemia (alcoholism, loop/thiazide diuretics, PPIs, diarrhea): hyperreflexia, tremors, tetany, refractory hypokalemia/hypocalcemia, and Torsades de Pointes (polymorphic VT); Hypermagnesemia (renal failure or excessive IV MgSO4 in preeclampsia): sequential loss of deep tendon reflexes (patellar reflex lost at > 4 mEq/L), lethargy, hypotension/bradycardia, respiratory depression (> 10 mEq/L), and cardiac arrest -> immediate antidote is IV Calcium Gluconate.
19	What are the nursing care priorities for an Arteriovenous Fistula (AVF) or Graft in a hemodialysis patient?	Assess patency every shift by palpating for a continuous 'thrill' (vibration) and auscultating for a 'bruit' (whooshing sound); NEVER take blood pressures, perform venipuncture, start IV lines, or apply tight tourniquets/restraints on the extremity with the AV access.
20	Why do Serum Calcium and Serum Phosphate have an inverse relationship in parathyroid disorders, and what life-threatening syndrome causes acute severe Hypophosphatemia (< 1.0 mg/dL)?	Parathyroid hormone (PTH) increases renal calcium reabsorption while inhibiting proximal tubular phosphate reabsorption (phosphaturia), keeping the Ca × PO4 solubility product constant; acute severe Hypophosphatemia (along with hypokalemia and hypomagnesemia) is the hallmark of Refeeding Syndrome when carbohydrates/insulin are reintroduced to a chronically malnourished or alcoholic patient, depleting ATP and 2,3-BPG and causing respiratory muscle failure, rhabdomyolysis, and hemolysis.
21	On a urine dipstick, what does a positive 'Heme / Blood' reaction with ZERO red blood cells seen on microscopic examination signify?	Either Myoglobinuria (from Rhabdomyolysis — skeletal muscle breakdown with markedly elevated serum Creatine Kinase > 5,000–10,000 U/L and hyperkalemia) OR Hemoglobinuria (from intravascular hemolysis with low haptoglobin and elevated LDH).
22	What is the 'AEIOU' mnemonic for the emergent indications for Hemodialysis in Acute Kidney Injury or CKD?	A — Acidosis (severe refractory metabolic acidosis, pH < 7.1); E — Electrolytes (severe refractory hyperkalemia > 6.5 mEq/L or rapidly rising); I — Intoxications (dialyzable toxins: Lithium, Methanol, Ethylene glycol, Salicylates, Valproate, Isopropanol); O — Overload (diuretic-refractory fluid overload / pulmonary edema); U — Uremia (uremic pericarditis/tamponade, uremic encephalopathy/seizures, uremic bleeding).
23	What are the six KDIGO stages of Chronic Kidney Disease (CKD) based on eGFR (G1 to G5)?	G1: eGFR >= 90 mL/min/1.73 m² (with albuminuria/structural kidney damage); G2: eGFR 60–89 (mildly decreased); G3a: eGFR 45–59 (mild-to-moderate); G3b: eGFR 30–44 (moderate-to-severe); G4: eGFR 15–29 (severe reduction, prepare for renal replacement); G5: eGFR < 15 mL/min/1.73 m² or dialysis (Kidney Failure / ESRD).
24	Why must iodinated IV contrast media and Metformin be managed carefully in patients with impaired renal function (eGFR < 30–60 mL/min/1.73 m²)?	Iodinated contrast can cause Contrast-Induced Nephropathy (CIN; prevented by pre- and post-procedure isotonic IV 0.9% NaCl hydration and holding nephrotoxins like NSAIDs); Metformin is excreted unchanged by the kidneys and is contraindicated when eGFR < 30 mL/min/1.73 m² (and held at the time of iodinated contrast if eGFR 30–60) because renal accumulation precipitates fatal Metformin-Associated Lactic Acidosis (MALA).
25	What are the clinical manifestations and ECG findings of Hypocalcemia (Total Ca < 8.5 mg/dL) versus Hypercalcemia (Total Ca > 10.5 mg/dL)?	Hypocalcemia: neuromuscular hyperexcitability, perioral/acral paresthesias, muscle cramps, laryngospasm, seizures, positive Chvostek and Trousseau signs, and PROLONGED QT interval on ECG; Hypercalcemia ('stones, bones, abdominal groans, thrones, and psychiatric overtones'): nephrolithiasis, bone pain, constipation/pancreatitis, polyuria (nephrogenic DI), lethargy/confusion, muscle weakness/hyporeflexia, and SHORTENED QT interval on ECG.
26	How does acute acidemia versus alkalemia alter free Ionized Calcium levels without changing Total Serum Calcium?	In alkalemia (e.g., respiratory alkalosis from hyperventilation), fewer H+ ions compete for negatively charged binding sites on albumin, increasing calcium-albumin binding and LOWERING free ionized calcium (triggering perioral numbness and carpopedal tetany); acidemia displaces Ca2+ from albumin, raising ionized calcium.
27	What are the normal adult serum reference ranges for Total Calcium (Ca2+), Ionized Calcium, Magnesium (Mg2+), and Phosphate (PO4-)?	Total Calcium: 8.5–10.5 mg/dL (9.0–10.5 mg/dL); Ionized Calcium: 4.5–5.6 mg/dL (1.12–1.40 mmol/L); Magnesium: 1.5–2.5 mEq/L (1.8–2.6 mg/dL); Inorganic Phosphate: 2.5–4.5 mg/dL.
28	How do you clinically and biochemically distinguish Nephrotic Syndrome from Nephritic Syndrome?	Nephrotic syndrome (podocyte foot-process damage: Minimal Change, FSGS, Membranous, Diabetic/Amyloid): massive proteinuria (> 3.5 g/24 hr or urine protein:Cr ratio > 3.5), hypoalbuminemia (< 3.0 g/dL), generalized pitting edema, hyperlipidemia/fatty casts, and hypercoagulability (loss of antithrombin III in urine); Nephritic syndrome (GBM inflammation: Post-streptococcal, IgA nephropathy, Lupus, RPGN): hematuria with acanthocytes/RBC casts, hypertension, oliguria/azotemia, and mild-to-moderate proteinuria (< 3.5 g/day).
29	What is the maximum safe rate of serum sodium correction in chronic hyponatremia, and what catastrophic complication occurs if corrected too rapidly?	Do not exceed a rise of 8 mEq/L (or 6–8 mEq/L in high-risk patients; absolute max 10–12 mEq/L) in any 24-hour period; overly rapid correction causes Osmotic Demyelination Syndrome (Central Pontine Myelinolysis), resulting in irreversible quadriplegia, pseudobulbar palsy, and 'locked-in' syndrome.
30	What are the normal adult reference ranges for Blood Urea Nitrogen (BUN), Serum Creatinine (Cr), and estimated Glomerular Filtration Rate (eGFR)?	BUN: 7–20 mg/dL (8–21 mg/dL); Serum Creatinine: 0.6–1.2 mg/dL (0.5–1.1 mg/dL in females, 0.7–1.3 mg/dL in males); Normal eGFR (calculated via the race-free 2021 CKD-EPI creatinine or combined creatinine-cystatin C equation): >= 90 mL/min/1.73 m² (with CKD defined as eGFR < 60 mL/min/1.73 m² or kidney damage markers such as UACR >= 30 mg/g persisting for >= 3 months).
31	How do you calculate Corrected Serum Calcium in a patient with hypoalbuminemia, and why does low albumin affect total calcium without changing ionized calcium?	Corrected Ca (mg/dL) = Measured Total Ca + 0.8 × (4.0 - Serum Albumin in g/dL); because ~40% of serum calcium is bound to albumin, hypoalbuminemia lowers total serum calcium while physiologically active free ionized calcium remains normal.
32	When is 3% Hypertonic Saline indicated in hyponatremia, and how is Syndrome of Inappropriate ADH (SIADH) managed?	3% hypertonic saline (100 mL IV bolus over 10 min) is reserved for acute symptomatic hyponatremia with severe neurological manifestations (seizures, coma, herniation) to acutely raise Na+ by 4–6 mEq/L; chronic euvolemic SIADH is managed with free water restriction, oral salt tablets + loop diuretics, urea, or vasopressin V2-receptor antagonists (tolvaptan, conivaptan).