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

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Ontology: Measurement of serum ionized calcium (C0201927)

Definition (NCI) The determination of the amount of ionized calcium present in a sample.
Definition (NCI_CDISC) A measurement of the ionized calcium in a biological specimen.
Concepts Laboratory Procedure (T059)
SnomedCT 391084000, 390320009, 389588006, 81316000
CPT 80047, 82330
English 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, Measurement of serum ionized calcium, Measurement of ionized calcium, Serum ionised calcium level (procedure), Calcium, serum, ionized measurement (procedure), CAION, Calcium, Ionized, Ionized calcium measurement, Calcium, serum, ionized measurement, Calcium, serum, ionised measurement, Serum ionised calcium level, Serum ionized calcium level, Serum ionised calcium measurement
Spanish medición de nivel sérico de calcio ionizado, determinación de nivel de calcio ionizado sérico, medición del nivel de calcio ionizado en suero (procedimiento), medición del nivel de calcio ionizado en suero, determinación de nivel de calcio ionizado sérico (procedimiento), medición de calcio ionizado en orina, medición de calcio ionizado, medición de calcio ionizado en orina (procedimiento)

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 143998003, 166700005, 271240001
English serum Ca++, Serum calcium, Serum Calcium Measurement, Serum calcium measurement, calcium levels serum, calcium serum, serum ca, serum calcium level, serum calcium test, calcium serum test, serum calcium, Serum calcium (& level) (procedure), Serum calcium (& level), Calcium - serum, Serum Calcium Test, Serum calcium level, Serum calcium measurement (procedure)
Dutch serum calcium
French Calcium sérique
German Kalzium im Serum
Italian Calcio sierico
Portuguese Cálcio sérico
Spanish Calcio en suero, 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