K. Mizunashi et al., THE EFFECT OF ENDOGENOUS PARATHYROID-HORMONE, EXOGENOUS CALCITONIN, AND DIBUTYRYL-CYCLIC-AMP ON URINARY-EXCRETION OF N-ACETYL-BETA-D-GLUCOSAMINIDASE, Calcified tissue international, 54(3), 1994, pp. 186-194
Urinary excretion of N-acetyl-beta-D-glucosaminidase (NAG) transiently
increases after PTH(1-34) infusion in idiopathic hypoparathyroidism (
IHP) but this response is impaired in pseudohypoparathyroidism (PHP) t
ype I. We investigated the effects of endogenous PTH, exogenous calcit
onin (CT), and dibutyryl cAMP (DBcAMP) on urinary excretion of NAG. Ur
inary NAG excretion in 14 patients with primary hyperparathyroidism (1
degrees HPT) was more than in normal subjects (P < 0.001) and decreas
ed after parathyroidectomy (P < 0.01). Urinary NAG excretion increased
after the infusion of 1.5 MRC/kg of eel CT in eight normal subjects (
P < 0.001), two patients with IHP, and a patient with PHP type Ib but
not in a patient with PHP type Ia. The increases of urinary NAG excret
ion by CT and by PTH(1-34) were positively correlated with the increas
es of urinary cAMP excretion (r = 0.752; P < 0.001 and r = 0.534; P <
0.002, respectively). Urinary NAG excretion increased after DBcAMP inf
usion in five normal subjects (P < 0.01), two patients with IHP, and t
wo with PHP type I. The increase of urinary NAG by 6.0 mg/kg of DBcAMP
was more than by 2.5 mg/kg of DBcAMP in normal subjects (P < 0.01). T
he increase of urinary NAG by 2.5 mg/kg of DBcAMP in PHP type I was co
mparable with that by 6.0 mg/kg in normal subjects, suggesting a hyper
responsiveness to DBcAMP in PHP type I. Urinary excretion of NAG is a
useful indicator of renal tubular responsiveness to PTH and CT. Cyclic
AMP-dependent mechanism is probably involved in PTH and CT-induced in
crease in urinary excretion of NAG.