The Importance of Diet in Managing Hypoparathyroidism
by Dr Karen K Winer (USA)
Calcium is maintained in the blood within a very narrow physiological range mainly through the actions of both Calcitriol and parathyroid hormone. The biologically active form of vitamin-D, Calcitriol (1,25 (OH)2 vitamin D3) is formed in the kidney by direct stimulation from parathyroid hormone which is secreted from the parathyroid gland.
Calcitriol increases intestinal calcium absorption. Parathyroid hormone also acts on the kidney to reabsorb calcium from the renal tubule. The combination of PTH action on the kidney and Calcitriol action on the intestinal tract to maintain calcium levels in the normal range. Adequate vitamin D is essential for calcium absorption in the intestinal tract.
The vitamin D in our body is from several sources. The cascade begins with a cholesterol derivative in the skin. This is converted to a precursor vitamin D3 molecule under ultraviolet radiation (sunlight). This is why our vitamin D levels are usually higher in the summer than in the winter. Exposure to sunlight (at least 10 minutes/day) generally prevents and can sometimes cure vitamin D deficiency. Other sources of vitamin D are from the diet, i.e. milk, meat, and vegetables. If vitamin D is lacking from our diet and we tend to work long hours indoors, a multivitamin containing 400 IU of vitamin D is an excellent source of vitamin D.
Patients with hypoparathyroidism have to plan to maintain a high-calcium diet on a daily basis. Instead of "high-calcium" diet, I really should say "optimal-calcium" diet. The amount of dietary calcium I recommend for patients with hypoparathyroidism is 1000-1500 mg. According to the NIH Consensus Statement, the current recommended calcium intake for the general population is 1000 mg. More calcium (1500 mg) is recommended for pregnant women and elderly people over the age of 65 years. Thus, the parent with hypoparathyroidism, is really taking approximately the same amount of daily calcium that is recommended for the general population.
The best source of calcium is dairy products, calcium-rich vegetables, and calcium fortified drinks. Milk products, such as yogurt, ice cream, and cheese provide us with most of our daily calcium. Many adults do not digest milk products well and may have some degree of lactose intolerance. In this case, one should try lactaid milk or calcium fortified orange juice. Milk products may seem to pose a problem for those who are watching their fat and cholesterol intake. There are many low-fat, low cholesterol options such as skim-milk, low-fat yogurt, low- fat cheese, etc. Salmon, sardines and Tofu are high in calcium.
In addition, you should keep in mind that high phosphorus levels are also a feature of hypoparathyroidism, since a lack of parathyroid hormone, phosphorous is not excreted in the urine and tends to rise in the blood. It is best to avoid high-phosphorous foods such as sodas and hot dogs. Milk is also high in phosphorous so should be ingested in moderation.
In hypoparathyroidism, it is important to maintain consistent level of dietary calcium intake to prevent large fluctuations in blood calcium. The 1000 mg of dietary calcium should be divided throughout the day, preferably into about 4 meals. This will help your medication work in maintaining normal levels of calcium in your blood. If you are taking vitamin D or Calcitriol, it is best to take your calcium supplementation (calcium carbonate) with your meals so that it is better absorbed.
I recommend to all my patients with hypoparathyroidism, to carry with them some form of calcium supplement (Tums ) or food that is high in calcium (calcium-fortified orange juice) for episodes of numbness, tingling, or cramping that one may experience with their blood calcium dropping below the normal range.
Karen K. Winer, M.D. National Institutes of Health 10 Center Drive MSC 1862 Bethesda, Maryland 20892-1862 (301) 435-6877
I want to express my sincere thanks to Dr. Winer for taking the time in her busy schedule to write the article for you. I hope that each of you will find the information presented useful in helping to maintain a healthy, normal life free from the problems associated with low levels of blood calcium. (James Sanders)