The kidneys have a number of responsibilities, including the filtering of wastes and toxins from the blood, regulation of blood volume and pressure, maintenance of electrolyte levels in blood and regulation of blood pH. Kidney function is entirely dependent on the flow of blood in the kidneys; as blood flow to the kidneys increase, more blood is filtered. Alcohol and caffeine can alter the kidneys' ability to filter blood.
Effects of Alcohol on the Kidneys
Alcohol interferes with the kidneys' ability to conserve certain electrolytes, including magnesium, calcium, sodium and phosphorus, that are lost in the urine as a result of alcohol consumption. However, potassium excretion is decreased, resulting in increased potassium levels in the blood. Alcohol is a potent depressant of the nervous system and when sufficient amounts are consumed it results in depression of the respiratory drive -- a series of mechanisms that ensure that a person is regularly breathing. When a person is hypoventilating, or breathing inadequately, acid accumulates in the blood, resulting in acidosis or low pH. The kidneys are responsible for normalizing a drop in pH caused by hypoventilation.
Complications Associated with Alcohol Abuse
The loss of electrolytes associated with alcohol use can result in impairments to heart function. Alcoholics tend to have poor dietary habits that result in vitamin deficiencies that in some cases can result in heart dysfunction. A problem with the heart affects every organ in the body, including the kidneys. Excess alcohol intake can result in heart or liver failure, which reduces the flow of blood to the kidneys. Decreased blood flow to the kidneys reduces the kidneys' capacity to filter blood effectively.
Effects of Caffeine on the Kidneys
According to a 2004 study published in "The Journal of Urology," prolonged intake of caffeine resulted in a moderately increased risk for calcium stone formation in the kidneys. Kidney stones usually affect one kidney at a time and are rarely associated with renal failure in a person with two intact kidneys. As one kidney fails, the other kidney takes up the functional load.
Symptoms of Kidney Failure
The initial stages of renal failure often occur without symptoms; as the various functions of kidneys are lost, symptoms begin to manifest. The kidneys stimulate the bone to produce red blood cells, which carry oxygen; red blood cell production decreases in renal failure, resulting in fatigue and shortness of breath. The kidneys produce bicarbonate to counteract increased acidity of blood. In renal failure, the reduced production of bicarbonate results in acid buildup in the blood; acidic blood interferes with the use of oxygen by cells, which results in organ failure. Several electrolytes excreted by the kidney also accumulate in blood; for example, high blood potassium interferes with heart rhythm, which can result in shortness of breath.
References
- "Alcohol Health & Research World"; Alcohol's Impact on Kidney Function; Murray Epstein M.D.; 1997
- "Journal of Urology"; Acute Caffeine Effects On Urine Composition And Calcium Kidney Stone Risk In Calcium Stone Formers; Massey LK; 2004
- "Harrison's Principles of Internal Medicine"; Kasper M.D., Braunwald M.D. and Fauci M.D.; 2005
