Know Your Kidney Hormones
Gypsies are born at a certain place, but roam all over the world mostly without purpose. Hormones, on the other hand, are born at one area but travel to different parts in the body with a specific purpose – to influence their function. Otherwise, they are exactly like gypsies. When we think of hormones, we usually think of insulin, thyroid hormones, sex hormones, growth hormone, etc. It is surprising for many to know that the kidneys also produce a variety of hormones which have local as well as far-reaching effects. Hormones and kidneys have a close relationship. The kidneys produces various hormones that act locally as well as at different sites and other organs produce hormones that act on the kidneys. Further, many hormonal diseases cause kidney problems.
The kidneys produce various hormones that act locally as well as at different sites and other organs produce hormones that act on the kidneys
Hormones Produced By The Kidneys
Erythropoietin, Vitamin D, Angiotensin Il, Kallikreins, Prostaglandins, Endothelins, and Adrenomedullin are hormones produced by the kidneys. Of these, Erythropoietin, Vitamin D and Angiotensin Il are most important.
Is produced by the kidney and transported to the bone marrow where it stimulates it to produce red blood cells in the presence of iron. Thus, kidney disease causes anaemia (low haemoglobin) due to erythropoietin deficiency. Of course, one needs to have a functioning bone marrow and adequate iron stores for erythropoietin to be effective.
To draw an analogy, a cloth-producing factory can produce cloth only if the factory-machinery (bone marrow) is working; there is enough raw material in the form of cloth (iron) and if the factory workers (erythropoietin) are working sincerely. Fortunately, with the advent of chemically engineered erythropoietin, kidney anaemia can easily be treated and corrected.
(Inappropriately named as it is a hormone, not a vitamin) is the other important hormone produced by the kidney.
There is a universal misconception that vitamin D is produced by the skin in response to early morning sun exposure. In reality, the skin produces inactive vitamin D. This inactive vitamin D is converted to active vitamin D in the kidney by a series of chemical reactions. Hence you may sit in the sun, but unless the kidney is functional, all you will ever get is sunburn or sunstroke!
Vitamin D is essential for maintaining calcium and phosphorus balance in the body which in turn maintains strong bones. Vitamin D deficiency in children causes rickets, bone deformities, and growth deficiencies. Vitamin D deficiency in adults causes bone weakness and fractures. Vitamin D supplements are now widely available in both oral as well as injectable form to offset vitamin D deficiency in patients with kidney disease.
After insulin and thyroid hormone, Angiotensin II is the most widely circulating and impactful hormone. It has a major role to play in maintaining blood pressure, salt and water balance, cardiac adaptations following heart attacks, blood vessel integrity, tissue growth regulation, and a myriad other functions. It is an extremely versatile hormone which has both good and deleterious effects depending on the circumstances under which it is released. Angiotensin Il is released by the kidneys in response to water, salt and blood pressure imbalances and acts on multiple organs apart from the kidneys.
The other kidney hormones Kallikreins are produced by the kidneys and act locally to regulate salt and water handling. Prostaglandins, Endothelins and Adrenomedullin are all produced by the kidney and act on blood vessel walls to maintain their integrity and stimulate them to contract and relax, thus modifying blood pressure levels as per the situation.
Hormones Produced By Other Organs That Act On The Kidney
- Aldosterone, Natriuretic Peptides, and Angiotensin are hormones that are produced in other organs but have their major effects on the kidney.
- Aldosterone is produced by the adrenal glands in response to dehydration. It influences the kidney to retain salt and water and excrete potassium. High levels of aldosterone produce high blood pressure.
- Natriuretic peptides are of three types. Atrial natriuretic peptide (ANP), Brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) are produced in the heart in cardiac failure and stimulate the kidney to excrete salt and water and lower blood pressure to reduce load on the failing heart.
- Angiotensin is a precursor of the important hormone, Angiotensin II. It is produced in the liver and facilitates release of Angiotensin II.
Apart from all these hormones that are closely related to the kidney, there are some hormonal diseases that can impact the kidney. The most well-known of these is diabetes which is the commonest cause of kidney disease worldwide. Parathyroid gland diseases cause kidney failure and kidney stones. Growth hormone excess causes a condition called acromegaly which is invariably associated with kidney disease.
Kidneys and hormones share a close relationship. The kidneys form a ‘production ground’ as well as a ‘battleground’ for various hormones. Hence, a ‘hormonious’ relationship between our kidney hormones is essential for a peaceful and harmonious life.