Bone profile patterns
What it means
Primary hyperparathyroidism: ↑Ca, ↑PTH, ↓PO₄ (adenoma). Vitamin D deficiency/osteomalacia: ↓Ca, ↓PO₄, ↑PTH (secondary), ↑ALP. CKD-MBD (secondary HPT): ↓Ca, ↑PO₄, ↑PTH, ↑ALP. Paget's: isolated ↑ALP with normal Ca/PO₄. Always interpret calcium corrected for albumin. Hypercalcaemia with a SUPPRESSED PTH = PTH-INDEPENDENT — malignancy (PTHrP, bone mets, myeloma), granulomatous disease (sarcoid/TB → ↑1,25-vitamin D), vitamin D excess. Key rule: hypercalcaemia should suppress PTH, so a PTH that is high or even mid-normal is INAPPROPRIATE and still means primary hyperparathyroidism.
Worked example
↑Ca with a PTH that is high OR inappropriately mid-normal + low phosphate → primary hyperparathyroidism. ↑Ca with a SUPPRESSED PTH + perihilar nodes → sarcoidosis.
In the exam
A woman has corrected calcium 2.9 with a PTH that sits in the middle of the reference range and a low phosphate.
What settles it
Primary HPT: high Ca + high or inappropriately-NORMAL PTH. Suppressed PTH + high Ca = PTH-independent (malignancy/sarcoid/vit D). CKD/secondary HPT: LOW Ca + high phosphate + high PTH.
Classically confused with
Iron studies interpretation
Source: NICE CKS — Hypercalcaemia / bone