The urine flow, sodium excretion rate, GFR, amount of sodium filtered and total solute excreted were decreased non‐significantly after inducing hypothyroidism by the oral administration of propylthiouracil; these changes are possibly due to a reduction of renal blood flow through a reduction of cardiac contractility and heart rate caused by a lowered level of thyroid hormone,50 in addition to a decrease in the sensitivity of the β‐adrenergic receptors, which in turn reduces the renin release and angiotensin II concentration.33 Here, REN is linked to hypothyroidism.