Hypocalcemia

Aka: Hypocalcemia, Low Serum Calcium, Serum Calcium Decreased

1. See Also
   1. Medication-Induced Hypocalcemia
2. Symptoms
   1. Cardiovascular (Systolic Dysfunction)
      1. Dyspnea
      2. Edema
      3. Palpitations
      4. Syncope
   2. Neurologic
      1. Headache
      2. Muscular fasciculations, Muscle cramping or spasms, Muscle stiffness
      3. Seizures
      4. Paresthesias
      5. Circumoral numbness
      6. Nervousness
      7. Weakness
   3. Gastrointestinal
      1. Vomiting
      2. Diarrhea
      3. Dysphagia
      4. Abdominal Pain
3. Signs
   1. Neurologic
      1. Tetany
      2. Carpopedal Spasm (Trousseau's Sign)
      3. Chvostek's Sign
   2. Skin
      1. Hair Loss (due to dry, brittle hair)
      2. Dry, puffy skin
   3. Eyes
      1. Premature Cataracts
      2. Papilledema
4. Diagnostics: Electrocardiogram (EKG)
   1. Prolonged QTc with severe Hypocalcemia
5. Labs
   1. Serum Calcium low
      1. Total Corrected Serum Calcium (for Serum Albumin) or
      2. Ionized Calcium
   2. Serum Electrolytes
      1. Serum phophate
      2. Serum Magnesium
      3. Serum Creatinine
   3. Parathyroid Hormone (PTH)
   4. Vitamin D
      1. 25-Hydroxyvitamin D
      2. 1,25-Dihydroxyvitamin D
6. Causes
   1. Miscellaneous and Multifactorial causes
      1. Hypoalbuminemia
         1. Use Corrected Serum Calcium for albumin or Ionized Calcium to interpret Calcium level
      2. Gram-Negative Sepsis (Marker for increased Sepsis related mortality)
         1. Zaloga (1987) Ann Intern Med 107(1): 36-41 [PubMed]
   2. Low Parathyroid Hormone (or normal Parathyroid Hormone level)
      1. Hypoparathyroidism
         1. Urine Calcium to Creatinine Ratio decreased
      2. Hypomagnesemia
      3. Calcium-sensing receptor activating mutation
         1. Serum Phosphorus increased
         2. Urine Calcium to Creatinine Ratio increased
   3. High Parathyroid Hormone (secondary Hyperparathyroidism as a reflex response to Hypocalcemia)
      1. Low Serum Phosphate
         1. See Medication-Induced Hypocalcemia
         2. Pancreatitis
         3. Vitamin D Deficiency
            1. Decreased 25-hydroxyvitamin D
      2. High or normal Serum Phosphate
         1. Acute Renal Failure or Chronic Kidney Disease
            1. Decreased 1,25-dihydroxyvitamin D
            2. See Renal Osteodystrophy
         2. Rhabdomyolysis
         3. Tumor lysis
         4. Pseudohypoparathyroidism
            1. Associated with adequate PTH levels, but a PTH receptor defect
            2. Associated with a shortened fourth digits on the hands and feet
7. Evaluation
   1. Confirm Hypocalcemia
      1. Obtain Corrected Serum Calcium (for Serum Albumin) or Ionized Calcium
      2. Correct Serum Calcium 0.8 mg/dl for every 1 gram Serum Albumin is below normal range
   2. Obtain labs to narrow causes (see labs above)
      1. Parathyroid Hormone
      2. Serum Electrolytes (Serum Phosphate, Serum Magnesium, Serum Creatinine)
      3. Vitamin D (25-Hydroxyvitamin D, 1,25-Dihydroxyvitamin D)
   3. Initial correction of abnormalities (if indicated)
      1. Correct Serum Magnesium if abnormal
      2. Immediate Calcium Replacement if symptomatic
   4. Identify underlying cause
      1. See causes above (based on lab findings as well as history and exam)
8. Management
   1. See Calcium Replacement
   2. Consider replacement if Corrected Serum Calcium <10 mg/dl
9. References
   1. Cooper (2008) BMJ 336(7656): 1298-302 [PubMed]
   2. Michels (2013) Am Fam Physician 88(4): 249-57 [PubMed]