Hypocalcemia

Overview

Hypocalcemia is a medical condition characterized by abnormally low levels of calcium in the blood serum. Normal blood calcium levels typically range from 8.5 to 10.5 mg/dL (2.12 to 2.62 mmol/L). When calcium levels fall below this range, it can affect numerous bodily functions, as calcium plays a crucial role in muscle function, nerve transmission, blood clotting, and bone health.

Calcium is one of the most important minerals in the body, with 99% stored in bones and teeth. The remaining 1% circulates in the blood and is vital for proper cellular function. The body maintains calcium levels through a complex system involving the parathyroid hormone (PTH), vitamin D, and calcitonin. When this system is disrupted, hypocalcemia can develop.

The condition can be acute or chronic. Acute hypocalcemia can be life-threatening and requires immediate medical attention, while chronic hypocalcemia may develop slowly and present with milder symptoms. The severity of symptoms often correlates with the rate of calcium decline rather than the absolute calcium level.

Symptoms

The symptoms of hypocalcemia can vary widely depending on the severity and rate of calcium decline. Some individuals with mild hypocalcemia may have no symptoms at all, while others may experience severe manifestations.

Common Symptoms

Classic Signs

• Trousseau's Sign: Carpopedal spasm induced by inflating a blood pressure cuff
• Chvostek's Sign: Facial twitching when tapping the facial nerve
• Tetany: Involuntary muscle contractions, particularly in hands and feet
• Perioral Numbness: Tingling around the mouth
• Paresthesias: Tingling sensations in fingers and toes

Causes

Hypocalcemia can result from various conditions that affect calcium absorption, metabolism, or regulation:

Primary Causes

• Hypoparathyroidism: Insufficient production of parathyroid hormone
• Vitamin D Deficiency: Inadequate vitamin D levels affecting calcium absorption
• Chronic Kidney Disease: Impaired vitamin D activation and phosphate retention
• Magnesium Deficiency: Required for proper PTH secretion and action
• Pancreatitis: Calcium precipitation in inflamed pancreatic tissue

Secondary Causes

• Medications (bisphosphonates, calcitonin, certain chemotherapy drugs)
• Post-thyroidectomy or parathyroidectomy
• Massive blood transfusions (citrate binding)
• Sepsis or critical illness
• Alkalosis (increases calcium binding to albumin)

Risk Factors

Several factors can increase the risk of developing hypocalcemia:

Diagnosis

Diagnosing hypocalcemia involves a combination of clinical assessment and laboratory testing:

Laboratory Tests

• Serum Calcium: Total and ionized calcium levels
• Albumin: To correct calcium levels for protein binding
• Parathyroid Hormone (PTH): To assess parathyroid function
• Vitamin D Levels: 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D
• Magnesium: Essential for calcium homeostasis
• Phosphate: Often elevated in hypocalcemia
• Kidney Function Tests: Creatinine and BUN

Additional Testing

• ECG to detect QT prolongation
• 24-hour urine calcium
• Genetic testing for hereditary causes

Treatment Options

Treatment of hypocalcemia depends on the severity, underlying cause, and presence of symptoms:

Acute Treatment

• Intravenous Calcium: Calcium gluconate or calcium chloride for severe symptoms
• Cardiac Monitoring: Essential during IV calcium administration
• Magnesium Replacement: If hypomagnesemia is present

Chronic Management

• Oral Calcium Supplements: Calcium carbonate or citrate
• Vitamin D: Calcitriol or other vitamin D analogs
• Dietary Modifications: Increased intake of calcium-rich foods
• Treatment of Underlying Cause: Managing kidney disease, hypoparathyroidism, etc.

Monitoring

Regular monitoring includes serum calcium, phosphate, magnesium, and kidney function. Patients on chronic therapy require periodic assessment to prevent complications like hypercalciuria and kidney stones.

Prevention

While not all cases of hypocalcemia can be prevented, certain measures can reduce risk:

• Maintain adequate dietary calcium intake (1000-1200 mg/day for adults)
• Ensure sufficient vitamin D through sun exposure or supplementation
• Regular monitoring if at risk (kidney disease, post-surgical)
• Proper management of underlying conditions
• Awareness of medications that can affect calcium levels
• Limit alcohol consumption and avoid excessive caffeine

When to See a Doctor

Seek immediate medical attention if you experience:

Schedule an appointment if you have:

• Persistent muscle cramps or weakness
• Chronic tingling sensations
• Risk factors for hypocalcemia
• Recent thyroid or parathyroid surgery

Related Conditions

Frequently Asked Questions