1. Biochemical Test Serum Calcium
to confirm increase in calcium as action of the parathyrod hormone
Normal: 8.5 mg/dL
Normal ionized: 4.4 – 5.2 mg/dL
Elevated calcium be tested with level of PTH for:
hyperparathyroidism
Malignancy
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2. Biochemical Test Parathyroid Hormone (PTH) Normal: 10 - 50 mg/dL
can distinguish PHPT vs other causes of hypercalcemia
hypercalcemia + intact PTH = PHPT
Hypercalcemia + low PTH = malignancy
Elevated parathyroid hormone (PTH) levels in the setting of hypercalcemia establish the diagnosis of hyperparathyroidism
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3. Biochemical Test Serum phosphate
decreased serum phosphate level of less than 2.5 mg/dL (0.81 mmol/L)
Cl: PO4 ratio is elevated = mild hyperchloremic acidosis (>33)
Calcium - Creatinine Ratio : elevated (>0.02)
Normal: <0.01
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4. Biochemical Test Urinalysis Alkaline phosphatase
For patients not previously documented normocalcemia or a family history of hypercalcemia
Elevated 24 hr urinary calcium: benign familial hypocalciuric hypercalcemia (BFHH)
>100 mg/day
Normal or increase in uric acid
Unchange or decrease in Mg
Alkaline phosphatase
increase due to Increased bone turnover reflected as elevated levels of markers of bone formation
marker of bone resorption is also noted: increase urinary pyridinoline
present in 10% of patients with PHPT
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5. Biochemical Test Vitamin D3 Normocalcemic PHPT
Occasionally normal of increased
Normocalcemic PHPT
Vit. D deficiency
Low serum albumin
Excessive hydration
High phosphate diet
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6. Laboratory test result
Serum calcium = 20 mg/dL elevated
Ionized calcium = 8 mg/dL elevated
Serum PTH level = 70 mg/dL elevated
Hypercalcemia + elevated PTH level
rule out malignancy
hyperparathyroidism
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