I. Physiology

  1. Parathyroid Hormone (PTH) modulates Serum Calcium
    1. PTH rises in response to low calcium
    2. PTH falls in response to high calcium
  2. Vitamin D modulates calcium gastrointestinal absorption
  3. Total body calcium distribution
    1. Skeleton: 98%
    2. Circulating: 2%
      1. Free or ionized Serum Calcium (active): 50%
      2. Albumin-bound Serum Calcium (inactive): 50%

II. Interpretation: Normal (normal range varies by individual labs)

  1. Serum Calcium: 8 to 10 mg/dl
  2. Ionized (free) Calcium: 4 to 5.6 mg/dl

III. Interpretation: Correcting Serum Calcium for Albumin

  1. No correction needed for Ionized Calcium
  2. Calculation 1
    1. Serum Calcium / (0.6 + (Total Protein/8.5))
  3. Calculation 2
    1. Calcium + ((Normal Albumin - Serum Albumin) x 0.8)
    2. Where normal albumin is often 4.0

IV. Interpretation: Abnormal

  1. Hypercalcemia
    1. Mild: Serum Calcium 10.5 to 12 mg/dl
    2. Moderate: Serum Calcium 12 to 14 mg/dl
    3. Critical: Serum Calcium 14 mg/dl or higher
  2. Hypocalcemia
    1. Serum Calcium under 8.0 mg/dl

Images: Related links to external sites (from Google)

Ontology: Measurement of serum ionized calcium (C0201927)

Definition (NCI) The determination of the amount of ionized calcium present in a sample.
Definition (NCI) A measurement of the ionized calcium in a biological specimen.
Concepts Laboratory Procedure (T059)
SnomedCT 391084000, 389588006, 390320009, 81316000
English Ionized calcium measurement, Measurement of serum ionised calcium, Serum ionized calcium measurement, Serum ionised calcium measurement (procedure), Measurement of serum ionized calcium (procedure), serum ionized calcium measurement (lab test), serum ionized calcium measurement, ionized calcium level, Ionized Calcium Measurement, calcium ionized measurements, ionized calcium measurement, CAION, Calcium, Ionized, Measurement of serum ionized calcium, Calcium, serum, ionized measurement, Calcium, serum, ionised measurement, Calcium, serum, ionized measurement (procedure), Serum ionised calcium level (procedure), Serum ionised calcium level, Serum ionized calcium level, Serum ionised calcium measurement
Spanish medición de calcio ionizado en orina (procedimiento), medición de calcio ionizado, medición de calcio ionizado en orina, Serum ionised calcium level, medición de nivel sérico de calcio ionizado, determinación de nivel de calcio ionizado sérico (procedimiento), determinación de nivel de calcio ionizado sérico

Ontology: Corrected serum calcium measurement (C0455288)

Definition (NCI) An estimate of serum calcium, corrected for the amount of albumin-bound calcium, used when albumin levels are not within normal ranges. It uses the formula: Corrected calcium (mg/dL) = measured total Ca (mg/dL) + 0.8 (4.0 - serum albumin [g/dL]), where 4.0 represents the average albumin level.
Concepts Laboratory Procedure (T059)
SnomedCT 166708003
English Corrected Serum Calcium Measurement, Corrected Serum Calcium, Corrected serum calcium level, Corrected serum calcium measurement (procedure), Corrected serum calcium measurement
Spanish determinación de nivel sérico de calcio corregido, medición sérica de calcio corregido (procedimiento), medición sérica de calcio corregido

Ontology: Serum calcium measurement (C0728876)

Definition (NCI) A quantitative measurement of the amount of calcium present in a sample of serum.
Concepts Laboratory Procedure (T059)
SnomedCT 166700005, 143998003, 271240001
English serum calcium, serum Ca++, Serum calcium, Serum Calcium Measurement, Serum calcium (& level) (procedure), Serum calcium measurement, calcium levels serum, calcium serum, serum ca, serum calcium level, serum calcium test, calcium serum test, Serum Calcium Test, Serum calcium level, Serum calcium measurement (procedure), Calcium - serum, Serum calcium (& level)
Dutch serum calcium
French Calcium sérique
German Kalzium im Serum
Italian Calcio sierico
Portuguese Cálcio sérico
Spanish Calcio en suero, Calcium - serum, Serum calcium (& level), Serum calcium, determinación de nivel sérico de calcio, medición sérica de calcio (procedimiento), medición sérica de calcio
Japanese 血清カルシウム, ケッセイカルシウム
Czech Kalcium v séru
Hungarian Szérum kalcium