Vitamin D (VitD)

Vitamin D is a derivative of steroids and can be divided into vitamin D2 and vitamin D3. Vitamin D2 is mostly contained in plant foods. It is synthesized from the ergosterol of plants by sunlight. Vitamin D3 can be synthesized from human skin and adipose tissue by 7-dehydrocholesterol. Vitamin D is a fat-soluble vitamin. Vitamin D from food is absorbed through the small intestine together with fat. It forms chylomicrons with the help of bile. It enters the bloodstream from the lymphatic vessels and is transported into the liver along with its own synthesized vitamin D3. In the liver, through the action of the monooxygenase system (25-hydroxylase) in hepatocyte microsomes, 25(OH)D3.25(OH)D3 is formed in the mitochondrial α-hydroxylase system of renal proximal tubular epithelial cells. It is converted to 1,25(OH)2D3, which is the largest biological action form of vitamin D. It can promote the synthesis of intestinal calcium-binding protein and increase the serum calcium and phosphorus content through the following three aspects: The absorption and operation of calcium and phosphorus increase the retention in the body. 2 Improve the reabsorption of calcium and phosphorus ions by the renal tubules, and reduce the discharge of urinary calcium and phosphorus. 3 When the calcium deficiency in the hypocalcemia diet, the absorption of calcium and phosphorus is promoted by the action of parathyroid hormone (PTH), and the release of calcium and phosphorus in the bone is mobilized. Therefore, in the initial stage of vitamin D deficiency, blood calcium is normal and blood phosphorus is slightly lower. When the vitamin D is further lowered, even if the secretion of PTH is increased, the amount of calcium absorbed back is small due to the decrease in the calcium content in the original urine, and the blood calcium is also lowered at this time. Basic Information Specialist classification: growth and development check classification: biochemical examination Applicable gender: whether men and women apply fasting: fasting Analysis results: Below normal: Reduction of 25-(OH)2D is seen in VD deficiency (rickets, rickets), severe liver disease, nephrotic syndrome, and reduction in sun exposure. 1,25-(OH)2D reduction is seen in VD-dependent type I, chronic renal insufficiency, severe VD deficiency, hypoparathyroidism, neoplastic hypophosphatemia osteomalacia, and excessive calcium intake. Normal value: 1,25-hydroxyvitamin D3: 62-156 pmol/L Above normal: An increase in 25-(OH)2D is seen in VD poisoning. 1,25-(OH)2D elevation is seen in VD-dependent type II, late pregnancy, VD deficiency, and neoplastic hypercalcemia. negative: Positive: Tips: When you take blood, you should relax and check with your doctor. Normal value 1,25-hydroxyvitamin D3 [1,25-(OH)2D]: 62 to 156 pmol/L (26 to 65 pg/ml). 25-hydroxyvitamin D3 [25-(OH)2D]: 37 to 200 nmol/L (15 to 80 ng/ml) in summer. Winter 35 ~ 105nmol / L (14 ~ 42ng / ml). Clinical significance First, 25-(OH) 2D detection: 1, elevated in VD poisoning. 2, reduced in VD deficiency (rickets, rickets), severe liver disease, nephrotic syndrome, reduced sun exposure. Second, 1,25-(OH) 2D detection: 1, elevated in VD dependent type II, late pregnancy, VD deficiency, neoplastic hypercalcemia. 2, reduced in VD dependent disease type I, chronic renal insufficiency, severe VD deficiency, hypoparathyroidism, neoplastic hypophosphatemia osteomalacia, excessive calcium intake. Low results may be diseases: vitamin D deficiency, vitamin D deficiency, hand and foot convulsions, high vitamin D poisoning results may be diseases: vitamin D deficiency rickets considerations Contraindications before examination: Dispose of preparations containing vitamin D3 before blood draw. Requirements for examination: When you take blood, you should relax your mind and check with your doctor. Inspection process Routine blood draw, check, test. Evaluation of laboratory diagnostic methods: 1, serum 25-hydroxyvitamin D3 determination: 25-hydroxyvitamin D3 is the main metabolite of vitamin D3, measured its value for early diagnosis, because the change of 25-hydroxyvitamin D3 precedes the change of bone, and fluctuates with the season These changes reflect the influence of a person's exposure to sunlight, and have more important clinical significance for the early diagnosis of rickets and osteoporosis syndrome. This test can also be used for follow-up after treatment for vitamin D deficiency, but it is more expensive and is not currently widely available. 2, blood biochemical examination: its change is earlier than the bone changes shown by X-ray images. The rise of blood alkaline phosphatase is earlier than the change of blood calcium and blood phosphorus. The recovery of blood alkaline phosphatase content during the recovery period of the disease precedes the recovery of blood calcium and blood phosphorus. Not suitable for the crowd A healthy group without vitamin D deficiency or excess. Adverse reactions and risks no.