Cardiorenal endocrine dynamics during volume expansion in hypothyroid dogs

Abstract

To address the role of atrial natriuretic factor (ANF) in hypothyroidism in the control of cardiorenal-endocrine function during volume loading, the relationships between atrial pressure, ANF, the renin-angiotensin-aldosterone system, and renal hemodynamic and excretory function were examined during and after acute 10% body wt saline volume infusion in pentobarbital-anesthetized hypothyroid dogs (n = 8). Hormonal changes before and after thyroidectomy were also evaluated. Four to 6 wk after thyroidectomy, ANF decreased and arginine vasopressin (AVP) and plasma renin activity (PRA) increased. Acute saline volume expansion caused an increase in ANF and decreases in AVP and PRA. Atrial pressure increased throughout volume expansion. Despite the absence of an increase in glomerular filtration rate (GFR) during volume expansion, urinary sodium excretion increased due to a marked rise in fractional excretion of sodium. These studies demonstrate that in hypothyroidism 1) ANF is decreased; 2) despite the decrease in basal ANF, increases in atrial pressure can stimulate relase of ANF; 3) despite the absence of an increase in GFR during volume expansion, fractional excretion of sodium increases associated with an increase in ANF; and 4) a lack of an increase in GFR during volume expansion is not related to an inability to increase ANF.

The Thyroid and the Kidney: A Complex Interplay in Health and Disease

“…Bradley et al (26) reported in hypothyroid rats that a decrease in glomerular surface area due to growth retardation may contribute to the decrease of GFR. Data from hypothyroid animals showed an adaptive pre-glomerular vasoconstriction mechanism in response to a filtrate overload due to deficient sodium and water reabsorption in the epithelial cells of the proximal tubule (50). Additionally, a chloride load in distal tubuli of hypothyroid rats, caused by a disturbed activity of chloride channels CIC-2, activated the tubulo-glomerular feedback leading to decreased GFR (49).…”

“…Hypothyroidism is associated with a decrease in transporter function and the opposite occurs (7) decreased (7) Peripheral vascular resistance decreased (7) increased (7) RAS activity increased (17) decreased (17) RBF increased (49) decreased (48,49) Glomerular vasoconstriction decreased (53) increased (50,51) Glomerular surface area increased (48) decreased (26) Tubulo-glomerular feedback increased (54) increased (49) Filtration pressure increased (53) decreased (48) GFR increased (11,12) decreased (8-10) Proteinuria increased (7) increased (7) Activity of tubular ion transport increased (65,66) decreased (56,59) Tubular mass increased (64) decreased (49) Urine concentrating ability decreased (68, 69) decreased (48) CO = cardiac output; GFR = glomerular filtration rate; RAS = renin-angiotensin system; RBF = renal blood flow.…”

Biochemical markers of liver and kidney function are influenced by thyroid function-a case-controlled follow up study in Indian hypothyroid subjects

“…Thyroid dysfunction may perturb liver function and vice-versa (4). In experimental animals, surgical or drug-induced hypothyroidism of a few weeks' duration has been shown to result in a decrease in GFR (6,7). However, clinical studies on hypothyroid subjects are very few and not much data is available on how hypothyroidism influences renal function in human beings.…”

Elevated Serum Creatinine Level in Thyroid Cancer Patients Undergoing Withdrawal of Thyroxine Therapy for Radioiodine Scan/Treatment

“…[1][2][3][4] In experimental animals, surgical or drug-induced hypothyroidism of a few weeks' duration has also been shown to result in a decrease in GFR. [5][6][7] However, the effect of hypothyroidism of short duration on GFR or serum creatinine level in humans has not been well documented.We retrospectively studied the prevalence of abnormally elevated serum creatinine level and the degree of its increase in patients who had undergone thyroidectomy for differentiated thyroid cancer and in whom thyroxine therapy was withheld for four weeks in preparation for radioiodine scanning/treatment. …”

“…[1][2][3][4] In experimental animals, surgical or drug-induced hypothyroidism of a few weeks' duration has also been shown to result in a decrease in GFR. [5][6][7] However, the effect of hypothyroidism of short duration on GFR or serum creatinine level in humans has not been well documented.…”