What are the key components of a calcium physical exam?

Key Components of a Calcium Physical Examination

The calcium physical examination should include assessment of serum calcium levels (both total and ionized), urinary calcium excretion, and evaluation of signs and symptoms related to calcium disorders.

Laboratory Assessment

• Measure serum total calcium, with normal range typically between 8.6 to 10.3 mg/dL (2.15 to 2.57 mmol/L) for adults 1
• Consider measuring ionized calcium (free calcium) when more precise assessment is needed, with normal values ranging between 4.65 and 5.28 mg/dL (1.16 and 1.32 mmol/L) 2
• For patients with hypoalbuminemia, use corrected calcium formula: Total calcium (mg/dL) + 0.8 [4 - Serum albumin (g/dL)] 2
• Measure urinary calcium excretion using spot urine calcium/creatinine ratio to evaluate for hypercalciuria 1
• Assess serum phosphate levels, as calcium metabolism is closely related to phosphate balance 1
• Check parathyroid hormone (PTH) levels, especially when calcium abnormalities are detected 1
• Measure vitamin D levels (25-hydroxyvitamin D and 1,25-dihydroxyvitamin D) when evaluating calcium disorders 1
• Consider alkaline phosphatase (ALP) or bone-specific ALP to assess bone turnover 1

Physical Examination Signs of Hypocalcemia

• Test for Chvostek's sign: tap the facial nerve anterior to the ear to elicit facial muscle twitching 3, 4
• Perform Trousseau's sign: inflate blood pressure cuff above systolic pressure for 3 minutes to induce carpal spasm 3, 4
• Assess for neuromuscular irritability, tetany, and seizures in severe cases 3
• Evaluate deep tendon reflexes, which may be diminished or absent 4
• Look for mental status changes including irritability, confusion, or altered consciousness 4
• Check for papilledema in chronic cases 4

Physical Examination Signs of Hypercalcemia

• Evaluate for signs of dehydration (dry mucous membranes, poor skin turgor) 1
• Assess for muscle weakness and fatigue 5
• Check for gastrointestinal symptoms including nausea, vomiting, constipation 1, 5
• Evaluate for altered mental status ranging from confusion to coma in severe cases 5
• In infants and young children with Williams syndrome, look for extreme irritability, vomiting, constipation, and muscle cramps 1

Special Considerations for Specific Populations

• For patients with chronic kidney disease:

  • More careful assessment of calcium status is required as the fraction of total calcium bound to complexes increases 2
  • Maintain serum calcium levels within normal range (8.4-9.5 mg/dL), preferably toward the lower end 2

• For children with Williams syndrome:

  • Monitor for signs of hypercalcemia including irritability, vomiting, constipation, and muscle cramps 1
  • Evaluate for dehydration, hypercalciuria, and nephrocalcinosis 1
  • Perform renal ultrasonography if hypercalciuria is found 1

• For patients with X-linked hypophosphataemia:

  • Assess bone-specific ALP in adults (as ~50% of circulating ALP originates from hepatocytes) 1
  • Evaluate for rachitic or osteomalacic bones, which typically present with elevated ALP levels and low urinary calcium 1

Additional Imaging and Testing When Indicated

• Consider renal ultrasonography to evaluate for nephrocalcinosis in patients with hypercalciuria 1
• For patients with suspected bone involvement, radiographic evaluation may be necessary 1
• Brain MRI may be indicated in patients with neurological symptoms 1

Common Pitfalls to Avoid

• Failing to correct calcium values in patients with hypoalbuminemia can lead to misdiagnosis of calcium status 2
• Not considering the impact of acid-base disturbances on ionized calcium levels (a fall in pH of 0.1 unit causes approximately a 0.1 mEq/L rise in ionized calcium) 2
• Overlooking the need to assess both calcium and vitamin D status together, as they have complex interactions 1
• Neglecting to evaluate magnesium levels, as hypomagnesemia can cause hypocalcemia 4
• Failing to recognize that chronic calcium deficiency can lead to osteoporosis and increased fracture risk 1, 6