Vitamin D is fat-soluble and is mainly absorbed in the gut from food sources such as eggs, fish, cod liver oil and vitamin D-fortified milk; they are rich sources of vitamin D. Vitamin D is initially inactive but is then processed by the liver and kidneys to become active. Vitamin D facilitates the absorption of calcium. Diseases that damage the lining of the intestines, for example Crohn's disease, reduces the absorption of vitamin D. Low vitamin D reduces calcium in the blood.
Crohn's Disease
The entereocytes, are cells of the intestine that are involved in absorption; they have finger-like projections called villi, which increases the surface area for the absorption of nutrients. In Crohn's disease, there is inflammation, or irritation, of the intestinal lining. The intestinal lining is full of enterocytes. Irritation of the intestinal lining results in reduced capacity for absorption, thereby affecting the uptake of nutrients. Vitamin D is poorly absorbed as well.
Complications
Crohn's disease reduces the absorption of vitamin D by damaging the intestinal lining. Poor absorption of vitamin D leads to low blood calcium. Low blood calcium is a problem for the heart, which requires adequate amount of calcium in blood to function properly. Low blood calcium causes an irregular pulse. Very low blood calcium is a potential cause of irreversible heart failure.
Low blood calcium leads to an increased secretion of parathyroid hormone from the parathyroid gland . Excess parathyroid hormone release causes excessive bone breakdown, leading to weakening of the bone.
In Crohn's disease, there is poor absorption of vitamin B12 and folate; deficiency in either leads to anemia.
Associated Symptoms
The heart is weakened by very low calcium; this causes shortness of breath while lying down. Low blood calcium also causes leg and abdominal swelling.
Low blood calcium causes tetany, a condition of uncontrollable muscle contractions. It causes strange sensations over the lips and tongue; it also causes abnormal twitching of the facial muscles.
Low blood calcium by itself leads to weakening of the bone, because calcium is needed to form a strong and healthy bone. Excessive parathyroid hormone released as an effect of low blood calcium also weakens bone by stimulating the breakdown of bone in order to release calcium to blood. This breakdown of bone results in bone and joint pain; other symptoms are generalized weakness, abdominal pain, nausea and depression.
Individuals with Crohn's disease commonly have diarrhea, which is also accompanied by abdominal pain. Poor absorption of vitamin B12 and folate leads to anemia, thereby resulting in tiredness and weakness.
Evaluation
Evaluation of vitamin D deficiency begins with the extraction of blood from a vein of the arm. The sample of blood is sent to the lab for analysis; levels of vitamin D are measured . A normal level of active vitamin D should be above 30 ng/mL; if less than 30 ng/mL, then it's abnormal. An active vitamin D level below 20 ng/mL is defined as vitamin D deficiency.
Treatment
There's no cure for Crohn's disease, but it can be controlled by anti-inflammatory drugs or drugs that reduced irritation of the intestinal lining; these drugs allow individuals affected to live a normal life. Vitamin D deficiency can result from Crohn's disease and should be treated by supplementation of vitamin D to prevent loss of bone density. The U.S. Department of Health & Human Services, recommends the supplementation of vitamin D at doses of 700 to 800 international units, or IUs, with 500 to 1,200 mg of calcium; this is effective in preventing loss of bone density.
Dietary modifications including the intake of fish, eggs, vitamin D-fortified milk and cod liver oil should be considered since these foods are abundant sources of vitamin D.
References
- MayoClinic.com: Hyperparathyoridism
- The Merck Manuals Online Medical Library: Vitamin D
- Weily Online Library: Severe Hypocalcemia: A Rare Cause of Reversible Heart Failure
- U.S. Department of Health & Human Services: Effectiveness and Safety of Vitamin D in Relation to Bone Health
- MayoClinic.com: Crohn's Disease
