NMS. Surgery

10

Part I ♦ Foundations 3. Treatment: Replace the chloride and volume deficit with sodium chloride solutions and replace K + as needed. B. Hyperchloremia (Cl − > 110 mEq/L) 1. Signs and symptoms: Muscle weakness, fatigue, thirst, hypertension. 2. Cause: Iatrogenic chloride in IV solutions. (The chloride content in normal saline [154 mEq/L] is significantly higher than that in plasma [90–110 mEq/L].) 3. Diagnosis/etiology: Excess chloride causes more water to dissociate and more H + ions to be present, leading to metabolic acidosis. 4. Treatment: Decrease the amount of chloride being infused.

V. Calcium A. Hypocalcemia (Ca ++ < 8 mg/dL)

1. Signs and symptoms: Neuromuscular irritability with perioral and extremity numbness that may progress to carpopedal spasm and tetany;

premature ventricular contractions. 2. Diagnosis/etiology (numerous)

a. Surgical patients: Removal of adenomatous or hyperplastic parathyroid glands and parathyroid injury during thyroid surgery. b. Critically ill patients: Lactate, citrate from blood transfusions, and medicines. c. Other: Vitamin D deficiency, chronic renal failure, intestinal malabsorption, excess dietary or therapeutic (laxative) magnesium, mercury exposure, chelation therapy. 3. Treatment a. Asymptomatic outpatients: Provide oral supplement. b. Symptomatic patients: Monitor and treat. (1) If symptoms are mild, then oral calcium is often sufficient. (2) Severely symptomatic patients should be repleted with IV calcium until symptoms resolve and an appropriate oral regimen is tolerated. B. Hypercalcemia (Ca ++ ≥ 10.5 mg/dL) 1. Signs and symptoms: Fatigue, confusion, nausea, vomiting, diarrhea, dehydration, and anorexia are common; when secondary to hyperparathyroidism, renal calculi and ulcer disease are more common. 2. Diagnosis/etiology (numerous) a. Endocrine: Primary hyperparathyroidism (most common), thyrotoxicosis. b. Malignancy: Most common (up to 20%–30% of cancer patients), often from osteolytic or parathyroid hormone-related protein (PTHrP) secreting lesions. c. Granulomatous disease: Sarcoidosis, tuberculosis. d. Medications: Excess calcium ingestion, vitamin D toxicity, thiazide diuretics. e. Other: Renal disease, milk alkali syndrome, familial hypocalciuric hypocalcemia.