Vitamin D deficiency : Dr R Padmakumar et al.

Vitamin D deficiency in a Surgeon’s perspective is relevant in

  • Parathyroid surgery
  • Bariatric surgery
  • Gallbladder surgery
  • Primary hyperthyroidism

Introduction:

Vitamin D is a fat soluble vitamin and produced by skin (from cholesterol) when exposed to ultraviolet B radiation (“sunshine vitamin”) and also obtained from dietary sources, including supplements. Most important components, vitamin D3 (cholecalciferol) comes from fortified foods, animal foods (fish, eggs and liver) and can be made internally when skin is exposed to ultraviolet (uv) radiation from the sun and vitamin D2 (ergocalciferol)

  • Deficiency: 25 (OH) D levels below 12 ng/ml
  • Inadequate: 25 (OH) D levels between 12-20ng/ml
  • An adequate: 25 (OH) D levels between 20-50ng/ml
  • Excessive: 25 (OH) D levels over 50nglml

Excessive intakes of vitamin D can lead to high levels of calcium (hypercalcemia). The symptoms of this are weakness, confusion, constipation, loss of appetite and development of painful calcium deposits. To avoid this, advice to keep the supplement intake below the tolerable upper limits.

Functions:

The need for vitamin D goes way beyond preventing and treating rickets. Various researchers have claimed that vitamin D benefits are associated with the following:

  1. Enhancing intestinal absorption of calcium and phosphorus
  2. Prevention of osteoporosis and osteopenia
  3. Allowing proper functioning of parathyroid hormone
  4. Lowering blood pressure in people with hypertension
  5. Lowering incidence and severity of cardiovascular disorders
  6. Decreasing the incidence of type 2 diabetes: research has shown that those with blood vitamin D level over 25ng/ml had a 43% reduced risk of developing type 2 diabetes compared with those with levels under 14ng/ml
  7. Decreasing inflammation: research has shown a decrease in levels of C-reactive protein , a marker of inflammation , with increased levels of vitamin D to just below 21ng/ml
  8. Reducing risk of allergies in children and adolescents
  9. Prevention of dental caries
  10. Prevention and treatment of depression
  11. Possibly helping with erectile dysfunction (ED)
  12. Regulating cholesterol levels in the blood: it has been shown that without adequate sun exposure, vitamin D precursors turn to cholesterol instead of vitamin D
  13. Decreasing mortality rate of certain cancers
  14. Increase immunity
  15. Deficiency in pregnancy may lead to gestational diabetes, pre eclampsia and small infants

Deficiency : Causes:

  1. Inadequate sun exposure
  2. Limited oral intake
  3. Impaired intestinal absorption
  4. Primary hyperparathyroidism
  5. After bariatric surgery
  6. After Gallbladder surgery
  7. Parathyroid removal
    • Accidental during thyroid surgery
    • For parathyroid adenoma or hyperplasia

Correlation of calcium level in vitamin D deficiency

  • If parathyroid function is normal
  • When primary hyperparathyroidism

In vitamin D deficiency due to reduced oral intake or reduced sun exposure ,Vitamin D level and calcium level will be low with normal parathyroid function. Calcium level will be high and vitamin D will be low when primary hyperparathyroidism exists.

Primary hyperparathyroidism

  • There is high calcium level in the blood
  • May present with parathyroid tumor
  • High PTH takes calcium from the bone and shut down calcium absorption
  • There will be low vitamin D

Obesity and after bariatric surgery

Research has begun to show a relationship between BMI and vitamin D deficiency. A study done on 2,187 overweight and obese subjects, found that those with a BMI above 40 had 18% lower serum vitamin D levels than those with a BMI under 40. Some possible reasons for this are lower intakes of vitamin D , less exposure to sunlight (uv) radiation and a higher distribution volume of vitamin D . Even with exposure to sunlight, there remains a risk for deficiency.

Morbid obese patients have a higher incidence of high PTH and low vitamin D even before surgery compared with normal individuals.

In gastric bypass: low calcium absorption due to bypassed duodenum and jejunum may be the cause.

In sleeve gastrectomy the vitamin D and calcium level are maintained within normal limits compared to bypass surgery.

Gall bladder Disease and vitamin D deficiency

Low vitamin D may cause gallbladder stone formation

Gall bladder removal may reduce vitamin D and magnesium levels. This may be due to reduced absorption of fat soluble vitamins (D, E, A and K).

People with compromised liver or digestive function are often vitamin D deficient. Exposure of skin to the sun’s UVB rays enables body to manufacture vitamin D. However, this process occurs in the liver and kidneys. Here people with a sluggish liver often do not manufacture vitamin D adequately.

Treatment

  1. Sun rays exposure
  2. Increased oral supplements
  3. When the blood level of vitamin D is below 30 ng/ml, a minimum of 1,000 IU/day will be needed for children and 1,500 to 2,000 IU/day of vitamin D3 for adults.
  4. Another rule of thumb is for every 1 ng/ml increase in blood level one need is an additional 100IU/day.
  5. In obese patients , with malabsorbtion syndromes and patients on medications affecting vitamin D metabolism, it is advised to have a higher dose (two to three times higher , atleast 6,000-10,000IU/day) of vitamin D to treat deficiency to maintain a 25(OH)D level above 30ng/ml, followed by maintenance therapy of 3,000-6,000IU/day.
  6. After parathyroid removal , may be wise to have a concomitant replacement of vitamin D with calcitriol (0.25-1mcg/day). Dependence on calcium supplementation for more than 6 months shows permanent hypoparathyroidism; which will necessitate continued use of such medications.