ABSTRACTS PRESENTADOS AL 11th INTERNATIONAL SYMPOSIUM "RADIONUCLIDES IN NEPHRO-UROLOGY", REALIZADO EN MONTEREY, CALIFORNIA, 13-17 MAYO 2001.

15. ACUTE EFFECTS OF THYROID HORMONE ON GLOMERULAR FILTRATION RATE: PRELIMINARY RESULTS.

E. Fommei, L. Mezzasalma, M. Scarlattini, G. Iervasi. Institute of Clinical Physiology, Department of Internal Medicine, University of Pisa.

fommei@ifc.cnr.it

Observational studies indicate a high prevalence of hypothyroidism in the general hypertensive population.
Cardiac output and peripheral resistances are influenced by triiodothyronine (T3), which has both and inotropic and vasodilatory effect. T3 also stimulates sympathetic activity, increases angiotensinogen and atrial natriuretic peptide and respectively decreases vasopressin levels. In the kidney, it increases GFR and decreases sodium reabsorption.
We here report the first preliminary results (phase 1: acute effects) of a study aimed to investigate a possible role of renal haemodynamic modifications in the relationships between hypothyroidism and arterial hypertension.
We studied six hypertensive patients with no renal disease and normal serum creatinine. Tc99m-DTPA scintigraphy was made twice, respectively before and 1.5-2 hrs after oral T3 (40µg) and GFR evaluated by the Gates method.
Plasma free T3 increased in all the subjects (from 2.45±69 to 8.30±2.35 pg/ml, means ± SD), whereas lesser variations were observed for GFR (from 84.50±32.99 to 91.17±38.60ml/min).
Definite data will be presented after having investigated a larger series of patients who are currently under recruitment. The results will possible clarify if T3 has either and immediate direct haemodynamic effect on GFR or rather a delayed "genomic" effect.