What is Hypovitaminosis D or Vitamin D Deficiency?
Hypovitaminosis D is nothing, but deficiency of Vitamin D. Hypovitaminosis D or Vitamin D deficiency can occur from inadequate sunlight exposure and/or insufficient nutritional intake of vitamin D. Other than this, certain medical conditions can hinder with the absorption of vitamin D and some disorders can impair the conversion of vitamin D into active metabolites, such as certain kidney, liver and hereditary disorders.
Hypovitaminosis D or Vitamin D deficiency causes impaired bone mineralization, which results in bone softening diseases, such as osteoporosis and osteomalacia in adults, and rickets in children. Hypovitaminosis D or Vitamin D deficiency is also thought to be related to the pathogenesis of non-alcoholic fatty liver disease.
Pathophysiology of Hypovitaminosis D or Vitamin D Deficiency
Hypovitaminosis D or Vitamin D deficiency is closely related to the development of pre-eclampsia in pregnant women. Hypovitaminosis D or Vitamin D deficiency causes impaired intestinal absorption of calcium, which leads to low levels of serum total and ionized calcium levels. Patient then suffers from secondary hyperparathyroidism from the hypocalcaemia. After this, the level of alkaline phosphatase is also usually increased. PTH increases bone resorption and also causes decrease in urinary calcium excretion while encouraging phosphaturia. All this causes hypophosphatemia, which aggravates the defect in mineralization in the skeleton. Hypovitaminosis D or Vitamin D deficiency is also related to the development of depression. If there is Hypovitaminosis D or Vitamin D deficiency in the mother, then it also affects the baby resulting in overt bone disease before the birth and decreased bone quality after the baby is born.
Signs & Symptoms of Hypovitaminosis D or Vitamin D Deficiency
Hypovitaminosis D causes lot of problems for the patient due to deficiency of Vitamin D, such as:
- Hypovitaminosis D or Vitamin D deficiency can also play a role in triggering depression.
- Patients suffering from Hypovitaminosis D are at an increased risk of fracture.
- Hypovitaminosis D or Vitamin D deficiency is thought to be related to progression of cancers, such as breast, ovarian, colon and prostate cancer.
- Patient suffering from Hypovitaminosis D or Vitamin D deficiency experiences light-headedness.
- There is muscle weakness and aches felt.
- Fasciculations occur, which is twitching of muscles due to reduced ionized calcium which occurs as a result of Hypovitaminosis D or Vitamin D deficiency.
- Osteoporosis occurs in adults, which is a condition characterized by increased bone fragility and decreased bone mineral density.
- Osteomalacia also is seen in adults with Hypovitaminosis D or Vitamin D deficiency. This is a bone-thinning disorder characterized by bone fragility and proximal muscle weakness.
- Periodontitis is bone loss from local inflammation of the gums, which can lead to loss of tooth in the patient.
- Rickets is a childhood disease where the patient has deformity of the long bones and impeded growth. The earliest sign of Hypovitaminosis D or Vitamin D deficiency is craniotabes, which is a condition where there is abnormal thinning or softening of the skull.
- Hypovitaminosis D or Vitamin D deficiency can be asymptomatic in some patients. However, symptoms which affect the bone mineralization develop which lead to failure in achieving the optimal bone mass. This in turn increases the risk of fracture in children as well as adults.
Vitamin D Deficiency & Depression
Hypovitaminosis D or vitamin D deficiency is a risk factor for depression. According to research, decreased level of vitamin D is associated with depression. Hypovitaminosis D also has a relation with perinatal depression and women having decreased levels of vitamin D have a higher risk for depression. Hypovitaminosis D is also thought to be a risk factor for depression in older individuals. Studies are going on to find out the relation between Hypovitaminosis D and depression.
Causes & Risk Factors for Hypovitaminosis D
- Sun Exposure: People with very little or no sun exposure is at an increased risk for having Hypovitaminosis D or Vitamin D deficiency.
- Age: As a person's age increases, so does the risk for Hypovitaminosis D or Vitamin D deficiency.
- Malnutrition: People with improper diet are at a higher risk for developing Hypovitaminosis D or Vitamin D deficiency. Hypovitaminosis D is the primary cause of rickets in young infants in many countries, as there is very less vitamin D in breast milk. Other than this, some climatic conditions and social customs prevent adequate exposure to sunlight. Hypovitaminosis D or Vitamin D deficiency in sunny countries, such as South Africa, Nigeria and Bangladesh, occurs among children and older toddlers due to low intake of dietary calcium.
- Obesity: Overweight people have decreased levels of the circulating form of vitamin D. This is because of decreased bioavailability of vitamin D3 from sunlight and food due to distribution in the adipose tissue.
- Lifestyle: Factors such as working outdoors or indoors also has an effect on the production of Vitamin D. people who remain indoors are more prone to develop Hypovitaminosis D or Vitamin D deficiency.
- Habitation: Hypovitaminosis D or Vitamin D deficiency is also related to urbanisation where air pollution blocks the UV light along with increase in the number of people who work indoors. Elderly individuals usually get less exposure to UV light due to immobility, hospitalization, institutionalization and being housebound; all this leads to Hypovitaminosis D or Vitamin D deficiency.
- Malabsorption: Hypovitaminosis D is seen more in individuals who have untreated celiac disease, exocrine pancreatic insufficiency from cystic fibrosis, inflammatory bowel disease, and short bowel syndrome, as all these conditions cause malabsorption.
- Darker Skin Color: People with darker skin are at an increased risk for Hypovitaminosis D or Vitamin D deficiency, as the melanin in the skin acts like a sun-block, because of which they may need extra vitamin D to avoid Hypovitaminosis D at higher latitudes.
- Cancer: According to research, hypovitaminosis D can be related to a poor prognosis for certain cancers, however, there is insufficient evidence for prescribing vitamin D for cancer patients.
Diagnosis of Hypovitaminosis D
A simple blood test is sufficient to find out if the patient has Hypovitaminosis D or vitamin D deficiency. There are two blood tests for Hypovitaminosis D. First one is 1,25 (OH)2D. This test shows the amount of vitamin D produced in the skin and the amount of vitamin D that is taken from the diet. This test, however, does not show the amount of vitamin D that is present in other tissues of the body. This test is not often beneficial in determining the status of vitamin D, as it has got a short half-life of 15 hours and is strongly regulated by parathyroid hormone, phosphate calcium, so much that there is no significant decrease seen until the Hypovitaminosis D is well advanced.
The test which is preferred for detecting Hypovitaminosis D is the 25-hydroxyvitamin D, also written as 25(OH)D. This quite accurately measures the current status of Vitamin D, the amount which you get from supplements, from diet and from the sun.
Treatment for Hypovitaminosis D
Treating Hypovitaminosis D requires replacing the vitamin D; and the amount required depends on the severity of the deficiency, patient's health risks and the time of the year. Initial treatment for Hypovitaminosis D or Vitamin D deficiency consists of high-dosage of Vitamin D until the desired serum levels of vitamin D are reached. This is then followed by maintenance dose for maintaining the acquired vitamin D levels. The lower the serum concentration of 25(OH) D in the patient, the more is the dosage required for treating Hypovitaminosis D to reach a satisfactory serum level.
The manner of taking Vitamin D supplements is also important. They should be taken with a fatty meal to help with absorption. There are various supplements which can be taken on a daily, weekly, or monthly basis. It depends on the patient's preference. Patient may be started at a higher dose, which is then decreased after a month or two. The aim is to get the level greater than 30-40 ng/mL, and then follow it with a maintenance dose. After taking the supplements for two to three months, it is advised that the patient get tested again to be sure that the levels are increasing.