Hormones and the kidney

As producers of hormones the kidneys are an endocrine organ. Hormones that are produced in the kidneys include 1,25-dihydroxyvitamin D3, renin and angiotensin, and erythropoietin. The kidney also contributes to the circulating pool of growth factors such as insulin-like growth factor-1 (IGF-1). Moreover, the kidneys participate in the regulation of hormonal action by eliminating hormones from the circulation, primarily polypeptide hormones. Renal elimination contributes significantly to the degradation of many peptide hormones and, to a lesser extent, catecholamines and some steroid hormones (Box 10.2.1.1). Hence, in advanced renal failure the half-lives and serum levels of these hormones are altered. In addition, the kidneys are target organs for hormones. The nephron is a major or exclusive receptor-bearing site for some hormones, and several other hormones are important in the regulation of aspects of renal function (Box 10.2.1.2). Certain abnormalities in the levels and activities of some of these latter hormones play significant roles in chronic renal failure and the progression of renal disease, and inhibitory therapeutic interventions are important treatment strategies in some renal diseases.