Complications of Alcohol – Kidney Link

 

Alcohol can cause all kinds of damage to the kidneys.  These effects can range from cell damage and enlargement of the kidneys to alcohols’ impact of the various hormones that control kidney function.  Alcohol creates an ionic imbalance in the body that can negatively affect many metabolic processes.

 

Kidney Function

 

The normal function of the kidneys is to filter and remove the metabolic wastes that build up in the body’s blood stream while at the same time controlling the body’s water and solute balance.  The wastes from muscle activity, food processing, and liquid consumption travel through the blood stream and into the kidneys where these wastes are filtered and removed as urine.  The urine travels through collection tubes called ureters and then accumulates in the bladder from which it exits the body through natural means (see figure 1).

 

On average, a healthy kidney can filter 200 quarts of blood in one day.  Most of the liquid and solute are quickly reabsorbed into the blood stream as they pass through the complex network of tiny filters called nephrons.  Of the 200 quarts of blood that gets filtered through the nephrons, the body removes around 2 quarts of liquid and nutrient waste as urine.

 

 

 

 

Text Box: Figure 2.  Nephrons are the tiny filters in the kidneys.Text Box: Figure 1.  The Kidneys.Each kidney contains around one million nephron units.  Each nephron is a collection of thinly walled capillaries (smallest of the blood vessels) where waste can filter through the cell walls and can then be removed

 

as urine (see figure 2).  The constriction of these capillaries affects the filtering ability of the kidneys.  When the body needs to conserve water, the pituitary gland (located in the brain) excretes a hormone called vasopressin (also known as anti-diuretic hormone or ADH).  ADH causes the nephron filters to become permeable (yielding passage), retaining more water in the blood stream and allowing less water to be excreted in the urine.

 

Along with the filtration of excess water, the kidneys also regulate the concentrations of the ions sodium, potassium, magnesium, chloride, and phosphate.  These ions have to be in balance in the blood stream to maintain healthy metabolic processes.

 

The Impact of Alcohol

 

Alcohol destroys this delicate balance of the ions and water in the body by altering the filtering ability of the kidneys.  Although the exact mechanisms for how alcohol changes the kidney’s ability to function are not clearly known, the changes in ionic concentrations have been studied in humans and in animals for many years.  Kidney complications are even greater if a person has also been diagnosed with liver damage due to alcohol consumption.

 

Urination can be induced 20 minutes after a person consumes alcohol possibly due to alcohol affecting the availability ADH.  When alcohol inhibits ADH, the nephrons in the kidneys become less permeable to water, and more water travels through the ureters to the bladder.  More water leaving the body affects all the concentrations of the ions in the body, negatively affecting many metabolic processes.  Experimental results indicate that older people overcome this suppression of ADH more quickly than younger people do.  So younger drinkers can lose more water in their urine than older people do.

 

The kind of alcohol consumed can either increase or decrease the concentrations of certain ions in the blood stream.  Beer is low in dissolved nutrients.  When a person drinks beer, large amounts of water enter the body; that lowers the concentration of metabolic nutrients, and because of the effect of ADH impairment, an equal amount of water does not leave the body in the urine.  Fluid overload in the blood stream decreases the body’s ionic concentrations and can be very dangerous, especially for advanced alcoholics who also have liver disease.  The following table gives an overview of the effects of decreased ionic concentrations:

 

The Effects of Decreased Ionic Concentrations

Ion

Sodium

Potassium

Phosphate

Magnesium

Effects

- Impaired mental activity.

- Seizure in extreme cases.

- Increased thirst.

- Hormonal imbalance promoting fluid intake.

- Decreased blood acidity resulting in a breakdown of glucose and increased metabolic activity.

- Resulting low blood sugar.

- Possible enzyme impairment.

 

 

When a person drinks hard alcohol (such as whiskey or vodka), the ionic concentrations can increase in the blood stream.  The suppression of ADH causes more liquid to leave the body as water, and ionic concentrations left in the blood can rapidly increase as more ions (mostly sodium) are ingested with the alcohol.  Alcohol can also impact the muscle cells of the body, causing them to release ions (i.e. phosphate).  The effects of more ions in the blood stream impacts the water held in the cells of the body through osmosis.  Osmosis pulls the water that resides in the cells into the blood stream to counteract the ionic imbalance.  This drying effect can negatively impact the normal function of cells and organs.

 

The Effects of Increased Ionic Concentrations

Ion

Sodium

Potassium

Phosphate

Magnesium

Effects

-  Osmotic flow of water out of body cells to areas of high sodium.  

-  Osmotic flow of water out of body cells to areas of high potassium.  

- Creates a buffer imbalance in the blood.

-  Increase in blood pH.

- Possible enzyme impairment.

 

One alcohol drink can affect the normal function of a person’s kidneys.  While only severe alcoholics suffer from some of the complications, keep in mind that these ionic imbalances occur each time a person drinks.