Calcium, Serum
What This Test Measures
Most important mineral; regulated by PTH and vitamin D; abnormal in thyroid/parathyroid disorders and cancer.
Preparation
For patients post-parathyroidectomy or with hypoparathyroidism, standard reference ranges may not reflect clinical targets set by their endocrinologist. Corrected calcium (adjusted for albumin) is more meaningful than total calcium alone: Corrected Ca = Measured Ca + 0.8 × (4.0 − Albumin). The functional medicine community also notes that calcium should always be interpreted alongside PTH, Vitamin D, and magnesium — not in isolation.
Reflects common practices in thyroid, BHRT, and functional medicine communities. This may differ from standard clinical guidelines. Not medical advice — always discuss with your provider.
General guidelines only. Requirements vary by lab and individual. Confirm with your provider before adjusting any medications.
Turnaround Time
Varies by lab
Clinical Notes
Ionized calcium more accurate; total calcium affected by albumin levels
ICD-10 Codes
Common diagnosis codes associated with this test. Codes are assigned by your provider.
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Lab Codes
Proprietary codes used by each lab for this test.
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For informational purposes only
This page is for educational and research purposes only and does not constitute medical advice, diagnosis, or treatment recommendations. ICD-10 and CPT codes are assigned by your healthcare provider. Always consult a qualified healthcare provider before ordering any lab test or making decisions about your health.