USMLE/COMLEX 1 - Hypocalcemia Management

Already subscribed? Log in »

Here are key facts for USMLE Step 1 & COMLEX-USA Level 1 from the Hypocalcemia Management tutorial, as well as points of interest at the end of this document that are not directly addressed in this tutorial but should help you prepare for the boards. See the tutorial notes for further details and relevant links.

VITAL FOR USMLE/COMLEX 1

Definition and Classification

1. Hypocalcemia: Serum Ca < 8.5 mg/dL 2. Classification:

Chronic/Mildly Symptomatic: Ca > 7.5 mg/dL
Acute/Symptomatic: Ca ≤ 7.5 mg/dL

Clinical Presentation

1. Symptoms may include: muscle spasms, tingling, lethargy, seizures, and QT interval prolongation

Etiology

1. Common causes: hypoparathyroidism, vitamin D deficiency, and chronic kidney disease

Management

1. Acute/symptomatic treatment: IV bolus 1-2 g calcium gluconate followed by infusion 2. Chronic/mild treatment: Oral calcium supplementation (1-2 g calcium gluconate daily, divided doses)

HIGH YIELD

Acute Management Details

1. IV calcium administration: bolus of 1-2 g calcium gluconate 2. Maintenance therapy: 1000 ml infusion of 1 mg/ml elemental calcium at 50mg/hr 3. Monitoring: Measure serum calcium levels daily in acute cases

Chronic Management Details

1. Oral supplementation: 1-2 g of calcium gluconate daily in divided doses 2. Monitoring: Check serum calcium weekly 3. Post-stabilization: Switch to oral calcium after stabilization of acute cases

Special Considerations

1. Hypoparathyroidism: Initiate calcitriol with oral calcium 2. Electrolyte imbalances: Correct hypomagnesemia

Beyond the Tutorial

Below is information not explicitly contained within the tutorial but important for USMLE & COMLEX 1.

Clinical Assessment

1. Chvostek's sign: Facial muscle spasm when the facial nerve is tapped 2. Trousseau's sign: Carpopedal spasm induced by occluding blood flow to the arm

Laboratory Evaluation

1. Corrected calcium: Adjustment for albumin levels (↓ albumin → falsely ↓ total Ca) 2. PTH levels: Elevated in secondary hypocalcemia, low in hypoparathyroidism 3. Vitamin D levels: 25-OH vitamin D deficiency is a common cause

ECG Findings

1. Prolonged QT interval: Hallmark ECG finding 2. T wave changes: May see flattened or inverted T waves 3. Heart block: Severe hypocalcemia can cause varying degrees of heart block

Special Populations

1. Neonatal hypocalcemia: Can occur due to maternal hyperparathyroidism 2. Post-thyroidectomy: Common iatrogenic cause due to parathyroid damage 3. Pancreatitis: Acute pancreatitis causes hypocalcemia due to saponification