Thursday, September 23, 2010

2.11i Vitamin D, parathyroid and calcium

Physician's Notebooks 2  - - See Homepage
Chapter on Vitamins Continues
2.11i: Vitamin D - 10 November 2018

Vitamin D is made in your body from glucose
Dosage in the vitamin D in pills 
Vitamin D and the calcium (Ca) concentration in blood  
Importance of Food Source of Vitamin D 
Adequacy of Vitamin D in Blood 
Vitamin D overdose 
My Opinion 
Normal Blood Test Vitamin D a Protective Factor Against Multiple Sclerosis 
Vitamin D and Hypercalcemia - My Experience 

Vitamin D is made in your body from glucose; the sunlight on your body produces under-skin pre-vitamin D that becomes the active forms, 25 hydroxy-vitamin D (25-OH vit.D) in liver and 1,25 dihydroxy-vitamin D (1,25-DHD) in kidneys. So, if one gets enough sunlight on skin each day, no need of vitamin D in food. But since people started wearing clothes and having shelters we need vitamin D in food. Interestingly, my living place has a glass-panel, northern exposure that during winter months has complete sun rays from 9 AM to 1 PM, and recently I have lain without clothes and the sun shining on me through the opened panel (bare sunlight) for 30 minutes on my back and 30 minutes on my face, and it has resulted in upping my blood test vitamin D. Of course, this is not to be depended upon. Also, especially in summer, one has increased risk of skin cancers from sunlight on skin.
Dosage in the vitamin D in pills, 0.25 microgram (my usual capsule)
Vitamin D and the calcium (Ca) concentration in blood must be kept in narrow range. If too low, the muscles get irritable, the heart beats irregular, and bones weaken. If too high, kidney stones form, the tissues become rock-like and the heart may stop. And brain is very dependent on calcium; if it detects blood Ca dropping, it signals the parathyroid glands in your neck to release the parathyroid hormone, PTH, and that signals your kidneys to produce the most active form of vitamin D, 1,25-DHD, which increases absorption of the Calcium (Ca) from eating and increases turnover of Ca (formation of new bone to replace old) all of which raises the blood test Calcium. Before blood Ca hits a high danger level, the PTH production turns off. The blood test for PTH may go high in vitamin D deficiency.
   If not enough vitamin D or calcium in the blood for a normal calcium level, the only way to up the Calcium is to draw it out of the bones and this can lead in growing children to rickets and osteomalacia in adults, where bone becomes rubbery and deformed. In adults, a similar low calcium in bones is osteoporosis, where bone becomes brittle and breaks too easily; and it can occur even with adequate vitamin D.

Importance of Food Source of Vitamin D: Fortification of food with vitamin D is the most important preventive of vitamin D deficiency. The US government has mandated milk be fortified with 400 IU (10 microgram) vitamin D per quart, and dairy and other food staples equally fortified.
   The US FNB adequate intake can be satisfied drinking 3 glasses of milk. In USA and Japan you can easily buy low-fat, low-sodium milk in the Super that will give needed Ca, P, and vitamin D without the bad excess cholesterol and sodium of regular milk.

Adequacy of Vitamin D in Blood: Best test for vitamin D is measuring blood serum concentration of 25-OH-D. The blood sample should be 10 AM after overnight fast and no sun bathing previous 24 hrs and no taking vitamin D pill, and normally it ought to be between 14 and 40 ng/mL (In European SI, 35 to 100 nM/L). It is useful as part of the bone metabolism screen that should include PTH, Ca, IP (inorganic phosphorus) Mg and Testosterone (for older men) or E2 estrogen (for older women).

Vitamin D overdose gives kidney stones and unpleasant calcification in tissues other than bone. It is source of the very high blood test Ca and P levels of kids whose soccer moms overdose them with vitamin D. I've seen such a kid. His blood tests raised a hullabaloo until his soccer mom told of dosing him with vitamin D pills.

My Opinion: Drink low-fat, low-sodium milk and eat Ca-containing food. (Crunch your shrimp shell in eating) Women over 50 and older men should monitor osteoporosis with at least one bone density imaging test. The use of calcium carbonate (or other Ca compound) pills and vitamin D can stop the osteoporosis of aging. I use calcium carbonate 500 mg and vitamin D (D3 - hydroxy cholecalciferol) 0.25 microgram (10 IU) 1 to 2 times a day on and off since age 75 - now 10 years. It may make hard stool and constipation which is no problem if you use your finger to take out the stool. My bone mineral density tests prove that oral calcium and vitamin alone can prevent and reverse osteoporosis. No need for Fosamax  or like medications.The gratifying end result is protection against bad fractures from falls.
Normal Blood Test Vitamin D a Protective Factor Against Multiple Sclerosis Another reason to routinely at year or more intervals check your blood test vitamin D is that even slightly low vitamin D is a risk factor for Multiple Sclerosis.
Vitamin D and Hypercalcemia - My Experience:  The daily oral calcium and vitamin D significantly upped my blood test calcium levels from ave 8.7 (before the pills) to ave 9.2 mg% after being on the Ca and D, and this is worrisome because it may increase cardiovascular risk for atherosclerosis of the large arteries and bad calcification of other parts of my body. Because of this worry I tend to limit my daily calcium and vitamin D pills to one a day without being ultra strict about it.

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