1,25-Dihydroxy Cholecalciferol (Calcitriol) is the biologically active form of vitamin D.

It is produced in the kidneys from 25-hydroxy vitamin D under regulation by parathyroid hormone (PTH).

Clinical uses include:

Diagnosing calcium and phosphate metabolism disorders.

Evaluating parathyroid gland function.

Detecting renal disorders affecting vitamin D activation.

Assessing bone diseases such as rickets, osteomalacia, and osteoporosis.

The test is performed using a blood sample.

Analyte: Serum 1,25-dihydroxy vitamin D (calcitriol).

Normal Range: ~18 – 78 pg/mL (varies by lab).

Abnormal Findings:

High levels: May indicate primary hyperparathyroidism, sarcoidosis, or certain lymphomas.

Low levels: Suggest chronic kidney disease, hypoparathyroidism, or vitamin D deficiency.

Clinical Use:

Provides insight into active vitamin D status.

Helps differentiate causes of abnormal calcium/phosphate balance.

Guides treatment in metabolic bone and endocrine disorders.