Vitamin D is a fat soluble prohormone, which means it is a forerunner to a hormone.  In humans, this vitamin is needed to keep blood calcium and phosphorus levels within normal ranges.  In addition, vitamin d facilitates calcium and phosphorus absorption.  This is helpful in ensuring appropriate growth in teeth and bones in humans.  Other important benefits of this vitamin include aiding insulin secretion, regulating blood pressure and enhancing immunity.  Vitamin D is unique in that it is absorbed with either ingestion or through the skin by sunlight exposure.  However, as vital as this vitamin is to humans, an overdose can lead to serious harmful, and sometimes fatal, consequences.

What Vitamin D Toxicity Means

Toxicity is the degree to which a substance is harmful and can cause damage.  If the substance is vitamin D, an excess amount causes a once helpful nutrient to become toxic, or poisonous.  The body naturally has a low vitamin D requirement on a daily basis.  Even 10 to 15 minutes of sunlight three times a week causes the body to produce sufficient of this vitamin so that an otherwise healthy person would not need supplemental vitamins.  However, since humans are unable to shut down its absorption process, high levels build up in the bloodstream.  When toxic levels are reached the body reacts negatively.

How Vitamin D Toxicity Occurs

This serious condition can be the result of taking an accidental overdose of the vitamin.  This has been known to happen frequently with people who take vitamin supplements or certain nutritional supplements with high a concentration of vitamin D.  Other causes of toxicity can be an error on the part of a doctor, pharmacist or even the patient taking vitamin supplements.  In rare cases the overdose is intentional, as in a suicide or homicide.

Symptoms of a Vitamin D Overdose

Too much of this substance in the bloodstream can manifest such symptoms as bone pain, weakness in the muscles, fatigue, and itchy skin.  Some people have experienced nervousness, dehydration and deafness.

Physical Damage Related to a Vitamin D Overdose

A patient suffering from vitamin D toxicity will have elevated blood calcium levels.  Loss of appetite is accompanied by vomiting and other symptoms.  Eventually, the body goes into kidney failure.  In pregnant women this toxicity can lead to the birth of a mentally or physically retarded infant.

Risk Factors

Patients with rickets may be more susceptible to this condition since they are usually prescribed supplements.  People with other vitamin D deficiency related conditions are also at risk for toxicity.  Vitamin supplements, or any other medication, should be kept away from young children, who may mistake colored pills for candy.

Prevention and Treatment

No specific antidote is available for vitamin D toxicity.  Some doctors have been known to cease vitamin therapy for the patient and to simply allow the excess to eliminate from the patient’s system over time.  Unfortunately, if kidney damage has occurred due to this condition it cannot be reversed.  Health screenings and counseling, including dietary counseling, have been helpful in the prevention of vitamin D overdose.