Relationship between serum TSH levels and intrarenal hemodynamic parameters in euthyroid subjects

Abstract

Objective: Low thyroid function may be associated with a reduced glomerular filtration rate (GFR) calculated on the basis of creatinine metabolism. Thyroid hormone directly affects serum creatinine in muscle and low thyroid function might exert a similar direct effect in the kidney. The goal of the study was to evaluate this possibility by assessment of the inulin-based GFR and to examine the mechanism underlying the reduction of GFR. Patients and methods: Renal and glomerular hemodynamics were assessed by simultaneous measurements of plasma clearance of para-aminohippurate (C PAH ) and inulin (C in ) in 26 patients with serum creatinine !1.00 mg/dl and without thyroid disease. All subjects were normotensive with or without antihypertensive treatment and were kept in a sodium-replete state. Renal and glomerular hemodynamics were calculated using Gomez's formulae. Results: Serum TSH, including within the normal range (0.69-4.30 mIU/ml), was positively correlated with vascular resistance at the afferent arteriole (R a ) (rZ0.609, PZ0.0010), but not at the efferent arteriole (R e ). Serum TSH was significantly and negatively correlated with renal plasma flow (RPF), renal blood flow (RBF), and GFR (rZK0.456, PZ0.0192; rZK0.438, PZ0.0252; rZK0.505, PZ0.0086 respectively). In multiple regression analysis, serum TSH was significantly positively associated with R a after adjustment for age and mean blood pressure. Conclusions: These findings suggest that low thyroid function, even within the normal range, is associated with reduced RPF, RBF, and GFR, which might be caused by a preferential increase in R a .

Plasma uric acid effects on glomerular haemodynamic profile of patients with uncomplicated Type 1 diabetes mellitus

“…Indirect intraglomerular haemodynamic parameters were estimated using equations derived by Gomez based on data from animal studies . These equations were successfully used in a similar manner to evaluate patients with conditions such as hypertension, endocrine disorders and Type 1 diabetes . Assumptions imposed by Gomez's equations were the following: (1) intrarenal vascular resistances are divided into afferent, post‐glomerular and efferent; (2) hydrostatic pressures within the renal tubules, venules, Bowman's space and interstitium ( P Bow ) are in equilibrium of 10 mmHg; (3) glomerulus is in filtration disequilibrium; and (4) the gross filtration coefficient ( K FG ) is 0.0867 ml/s/mmHg given a normal kidney physiology (GFR = 130 ml/min, oncotic pressure π G is 25 mmHg and P GLO = 60 mmHg, given Winton's indirect estimates in dogs that glomerular pressure is roughly two‐thirds of the mean arterial pressure (MAP) ).…”

Significant association between glycemic status and increased estimated postglomerular resistance in nondiabetic subjects - study of inulin and para-aminohippuric acid clearance in humans

“…(), that is, a simple method of C in and C PAH by single urine collection, as we have reported previously (Tsuda et al. , ,b). In brief, the subjects received 500 mL of water orally 15 min before the infusion.…”

“…() and the method reported previously by us (Tsuda et al. , ,b), inulin and PAH were administered by continuous intravenous infusion via the forearm antecubital vein in the morning, after fasting. C in and C PAH were measured simultaneously according to the method of Horio et al.…”

Relationship Between Serum Uric Acid Levels and Intrarenal Hemodynamic Parameters

“…Renal plasma flow (RPF) and glomerular filtration rate (GFR) were determined by the constant input clearance technique using PAH and inulin, respectively, as previous reported by us [14,15]. Continuous intravenous infusion of 1% inulin and 0.5% PAH via the antecubital vein was performed in the morning after an overnight fast, based on the method of Horio et al [16].…”

“…However, Gomez published a series of formulae for the indirect evaluation of glomerular hemodynamics in humans [9]. These formulae have been used to calculate glomerular hemodynamics in various conditions, including untreated and treated essential hypertension [9,10], renovascular hypertension in human [11], primary aldosteronism [12], and supraventricular tachycardia [13], and diabetic and non-diabetic subjects by us [14,15]. The aim of the present study was to evaluate the relationship between serum uric acid levels and renal hemodynamic parameters in humans, utilizing clearance of para-aminohippurate (C PAH ) and inulin (C in )…”