title: [Studies on the renal handling of urea nitrogen, creatinine, water and electrolytes in hyperthyroid patients with Graves' disease].
abstract: To delineate the pathophysiological basis for increased blood urea nitrogen (BUN), decreased serum creatinine (SCr) and increased BUN/SCr ratio in patients with hyperthyroidism due to Graves' disease, systematic evaluation on renal handling of solutes and water was carried out before and during treatment of the disease. First, BUN, SCr, serum sodium (Na), serum potassium (K), serum chloride (Cl), creatine kinase (CK), serum triiodothyronine (T3) and serum thyroxine (T4) were consecutively measured in 16 patients (aged 18-62 yrs, 4 males and 12 females) with Graves' disease before and during antithyroid drug therapy, and 16 healthy subjects (aged 22-64 yrs, 4 males and 12 females) served as controls. BUN (14.8 +/- 2.9 mg/100ml) was significantly higher (p less than 0.01), and SCr (0.62 +/- 0.16 mg/100ml) and CK (41.7 +/- 23.6 U/l) were significantly lower (p less than 0.01) in untreated patients compared to respective values in the control group (BUN, 13.2 +/- 2.9 mg/100ml; SCr, 0.87 +/- 0.16 mg/100ml; CK, 99.3 +/- 49.5 U/l). Consequently, BUN/SCr ratio was significantly elevated (p less than 0.01) in the patients. As T4 and T3 returned to normal, BUN, SCr, BUN/SCr ratio and CK of the patients also normalized. Serum electrolytes were not significantly different in the patients compared to the controls. Second, renal clearance of para-aminohippurate (CPAH), inulin (CIn), creatinine (CCr), free water (CH2O) and chloride (CCl) was evaluated in 7 untreated patients (aged 17-44 yrs, 4 males and 3 females) and in 7 controls (aged 24-39 yrs, 5 males and 2 females). In patients with untreated Graves' disease, CPAH, CCr and Curea were significantly greater than in the controls (847 +/- 367 vs 442 +/- 124 ml/min, p less than 0.05, 132.7 +/- 14.7 vs 76.6 +/- 14.4 ml/min, p less than 0.01, and 86.9 +/- 16.0 ml/min vs 52.1 +/- 12.6 ml/min, p less than 0.05, respectively). CIn was slightly but insignificantly increased in the patients (95.3 +/- 20.8 ml/min) compared to the controls (76.7 +/- 13.3 ml/min). As a result, CCr/CIn and Curea/CIn were significantly greater in the patients than in the controls (142.7 +/- 32.0 vs 100.7 +/- 7.1%, p less than 0.01, 92.4 +/- 18.7 vs 68.4 +/- 14.4%, p less than 0.05, respectively). The difference between CCr and CIn indicates that 40% of urinary creatinine is of tubular origin. Renal excretion of urea and creatinine was increased by 117% and decreased by 77%, respectively in the patients, but the differences were not statistically significant.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Department of Geriatrics, Endocrinology and Metabolism, Shinshu University School of Medicine.
authors.forename: T
authors.initials: T
authors.lastname: Shirota
mesh_terms: D000293:Adolescent; D000328:Adult; D001806:Blood Urea Nitrogen; D001834:Body Water / Q000378:metabolism*; D003402:Creatine Kinase / Q000378:metabolism; D003404:Creatinine / Q000378:metabolism*; D004573:Electrolytes / Q000378:metabolism*; D005260:Female; D006111:Graves Disease / Q000378:metabolism*; D006801:Humans; D007668:Kidney / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D014508:Urea / Q000378:metabolism*
chemical_list: D004573:Electrolytes; D014508:Urea; D003404:Creatinine; D003402:Creatine Kinase