Primary hyperparathyroidism is suggested by all of the following, except:
Answer is B (Low Urinary Calcium): Primary Hyperparathyroidism is associated with normal or increased urinary calcium levels. Increased PTH and Increased Serum calcium in association with high levels of urinary calcium suggest a diagnosis of Primary Hyperparathyroidism Increased PTH and Increased Serum calcium in association with low levels of urinary calcium suggest a diagnosis of Familial Hvpocalciuric Hvpercalcemia (FHH) Disorder S-Ca2+- S-PHOS Intact PTH PTHrP Urine Calcium Urinary Ca2+ Creatinine Clearance ratio Primary HPTH 1' sl, (or N) 1' (or N) ,I, U-Ca2' > 100mg/24h >0.02 Familial benign hypercalcemia l' .I(or N) 1' (or N) ,I, U-Ca2+ <100mg/24h <0.01 This clearance ratio is calculated from simultaneous fasting serum and urine Ca and creatinine measurements. The urine sample can be from a spot or a 24 h collection. The clearance ratio is calculated as follows: Urine Ca (mg/24h)x plasma creatinine (mg/dl )/plasma Ca (mg/dL) x urine creatinine (mg/24h)
Increased serum calcium
Low urinary calcium
Increased PTH
Increased C-AMP