PTH eval

iPTH should be eval with Sr. Ca levels, Sr. Phosphate and urine electrolytes to aid in its interpretation.

• • PTH: 7 - 53 pg/mL with Total Ca: 8.6 - 10.6 mg/dL = NORMAL

  • PTH: >53. Tot. Ca: >10.6 = 1° hyperparathyroidism

  • PTH: >53. Tot. Ca: <10.6 = 2° hyperparathyroidism

  • PTH: <45. Tot. Ca: >10.6 = Non-parathyroid hypercalcemia

  • PTH: <20. Tot. Ca: >8.6 - Hypoparathyroidism

Total Ca should be corrected for low albumin.

If blood pH is not normal, an ionized Ca should be done.

In primary hyperparathyroidism: hypercalcemia, PTH level in high-normal range; hypophosphatemia, hypercalciuria.

Clear surgical indications for primary hyperparathyroidism:

Serum Ca greater than 1 mg/dL above the upper limit of normal.

BMD by DXA: T-score < - 2.5 at lumbar spine, total hip, femoral neck, or distal 1/3 radius.

Vertebral fracture

Creatinine clearance < 60

24-h urine for calcium > 400 mg/d ( 10 mmol/d) and/or increased stone risk by biochemical stone risk analysis

Presence of nephrolithiasis or nephrocalcinosis by x-ray, ultrasound, or CT

< 50 yrs