Hypercalcemia

The patient with cancer who becomes confused and constipated isn't just uncomfortable — a calcium level above 10.5 mg/dL can silently progress to cardiac arrest.

Hypercalcemia is serum calcium above 10.5 mg/dL (or ionized calcium above 5.3 mg/dL). The two most common causes are primary hyperparathyroidism and malignancy — together they account for roughly 90% of cases. Excess calcium depresses neuromuscular excitability, so the clinical picture is the opposite of hypocalcemia: decreased muscle tone, diminished deep tendon reflexes, and sluggish smooth muscle. The classic memory cue is 'bones, stones, groans, and moans' — bone pain, kidney stones, abdominal complaints (constipation, nausea, anorexia), and neurological changes (lethargy, confusion, coma). On ECG, look for a shortened QT interval — the heart repolarizes faster with excess calcium. Severe hypercalcemia (above 14 mg/dL) is a medical emergency. First-line nursing interventions center on aggressive IV normal saline hydration to promote renal calcium excretion. Loop diuretics (furosemide) may be ordered if the patient develops fluid overload or has heart failure — they are not used routinely. Thiazide diuretics are contraindicated because they increase renal calcium reabsorption. You also encourage mobility — immobility accelerates bone calcium release, worsening the problem. Monitor I&O carefully; the client is at risk for dehydration and renal calculi. Safety precautions are essential because lethargy and confusion increase fall risk.

Key Distinctions

Don't confuse hypercalcemia (decreased neuromuscular excitability, constipation, shortened QT) with hypocalcemia (increased excitability, tetany, prolonged QT) — they are mirror opposites. Students mix up diuretic effects: loop diuretics waste calcium (helpful here), while thiazides retain calcium (contraindicated). Corrected calcium must be calculated when albumin is low — a 'normal' total calcium in a hypoalbuminemic client may actually be elevated.

Clinical Pearl

Bones, stones, groans, and moans — and never give a thiazide. Hydrate first, loop only if fluid-overloaded.