Essential Facts on the Go: Internal Medicine (21 page)

If chronic, aim to correct 6–8 mEq/L × 24 h

V_4_a
Hypokalemia

V_4_b
Hyperkalemia

V_5_a
Hypocalcemia

Normal serum levels: 8–10.5 mEq/dL

Adjust for hypoalbuminemia: serum calcium = calcium + 0.8 (4 – measured albumin)

Symptoms

• Chvostek sign: carpopedal spasm with BP cuff inflation

• Trosseau sign: contraction of ipsilateral facial muscles when facial nerve is tapped

• Prolonged QT

• Altered mental status

• Respiratory depression

• Increased Intracranial pressure/papilledema

Differential

• PTH mediated: low PTH — destruction of parathyroid glands (autoimmune, surgical, radiation): high PTH — pseudohyperparathyroidism (bone and kidney unresponsive to PTH)

• Vitamin D deficiency: vit D(OH)25 (dietary deficiency, lack of sunlight exposure); vit D(OH) 1,25 (advanced CKD, liver disease)

• Sequestration: cytoblastic bone lesions (breast, prostate); pancreatitis; hyperphosphatemia (tumor lysis syndrome, rhabdomyolysis), postmassive transfusion (citrate that is used as an anticoagulant in blood products, chelates calcium)

• Drugs: cinacalcet, bisphosphonates, calcitonin, 5FU/leucovorin, gadolinium

• Calcium sensing receptor abnormalities: autosomal dominant gain of function mutation = hypocalcemic hypercalciuria

• Hypomagnesemia

• Alkalosis

Management

• Severe/symptomatic: calcium gluconate 1–2g IVPB

• Treat vitamin D deficiency: ergocalciferol 50,000 units qwk until levels sufficient (>30) or cholecalciferol 1000–2000 IU/day until levels sufficient; CKD patients may require 1,25 dihydroxyvitamin D supplementation

• Hypoparathyroidism: **must treat with vitamin D + calcium combination to avoid nephrocalcinosis

V_5_b
Hypercalcemia

•
Normal calcium levels = 8.7–10.5 mg/dL

•
Severe hypercalcemia > 14 mg/dL

Signs and Symptoms

• Depression, fatigue, muscle weakness, constipation, nausea, AMS, polyuria, shortened QT, AKI

Etiology

• PTH mediated: primary/tertiary hyperparathyroidism

• 1, 25 dihydroxyvitamin D mediated: granulomatous diseases (sarcoid, TB, Crohn, lymphoma, silicone, etc)

• Malignancy: PTHrp mediated; 1,25 dihydroxyvitamin D mediated (lymphoma); lytic bone lesions (multiple myeloma)

• Familial: hypocalciuric hypercalcemia (inactivating mutation of CaSR)

• Other: hypervitaminosis A and D, milk alkali syndrome, thiazide diuretics, lithium, hyperthyroidism, immobilization

Workup