Vitamin D-dependent rickets
Introduction
Introduction to vitamin D-dependent rickets Vitamin D-dependent rickets (VDDR) is autosomal recessive, and its clinical features are similar to those of typical vitamin D deficiency, so it is also called pseudo-D deficiency rickets. basic knowledge The proportion of illness: 0.001% Susceptible people: children Mode of infection: non-infectious Complications: fracture, dwarfism, renal amino acid urinary rickets
Cause
Causes of vitamin D-dependent rickets
(1) Causes of the disease
The autosomal recessive inheritance causes the genetic defect of renal tubular epithelial cells 25(OH)D3-1 hydroxylase, which is caused by the decrease of 1,25(OH)2D3 or the lack of receptor.
(two) pathogenesis
The disease is an autosomal recessive hereditary disease, which may be caused by a deficiency in the active vitamin D3 produced by the kidney or due to a genetic defect of the renal tubular cell 25(OH)2D3-1 hydroxylase, which cannot be 25 ( OH) 2D3 is converted to 1,25(OH) 2D3. Due to the lack of 1,25(OH) 2D3, the intestinal absorption of calcium is reduced, resulting in hypocalcemia, secondary PTH increases, resulting in increased urinary phosphorus. Parathyroidism and rickets, due to the normal concentration of 25(OH)2D3 in the blood, it is not a true vitamin D deficiency, but a pseudo-deficiency. Some patients have high concentrations of 1,25(OH)2D3 in the blood, but these The affinity of the patient 1,25(0H)2D3 receptor is reduced (type II VDDR).
Prevention
Vitamin D-dependent rickets prevention
The disease is a hereditary disease, there is no specific preventive measures for its onset, and patients with already onset should be actively symptomatic to prevent complications.
Complication
Vitamin D-dependent rickets complications Complications, dwarfism, renal amino acid urinary fistula
The main complications are rickets and other bone disease changes, such as fractures, bone pain, dwarfism, etc., but also amino acid urine and high blood chlorine acidosis.
Symptom
Vitamin D-dependent rickets symptoms Common symptoms Abnormal withdrawal response Short stature muscle weakness Vitamin D Poisoning Bone pain Alkaline phosphatase increased
The disease is common in children, sick children usually appear symptoms 12 weeks after birth, rickets before 2 years old, its characteristics are similar to vitamin D refractory rickets, but this disease has sputum, severe muscle weakness, children more than 1 Osteopathic lesions begin to appear around the age of one year. The "O" shaped leg is often the earliest symptom of attention, but the disease is mostly neglected, the height is normal, and the sick child is short. Serious illnesses such as children can occur in the age of 6 years. Rickets, manifested as severe skeletal deformities, dwarfism, severe bone pain, some patients may suffer from bone pain and can not walk, severe cases may occur fractures and growth and development stagnation, and often before the occurrence of bone disease, early lesions, such as teeth Broken, worn, shedding, enamel too little, etc., laboratory examination showed that blood calcium decreased, blood phosphorus was normal or increased, and even decreased; alkaline phosphatase increased; blood parathyroid hormone increased; type I VDDR serum 1, 25(OH)2D3 decreased or could not be detected, type II VDDR increased; there may be amino aciduria and hyperchloremia acidosis.
Examine
Vitamin D-dependent rickets
1. Urine and feces check for decreased urinary calcium and increased urinary phosphorus; there may be amino aciduria and increased fecal calcium.
2. Blood test blood phosphorus value has individual differences, but the decrease is very small, blood calcium is lowered (blood calcium value is lower than 2.25mmol / L for hypocalcemia), alkaline phosphatase is elevated; blood parathyroid hormone Increased; may have high blood chlorine acidosis, type I VDDR serum 1,25 (OH) 2D3 reduced or not measured, type II VDDR increased.
Routine imaging examination and B-ultrasound examination, bone X-ray showed typical rickets and osteomalacia.
Diagnosis
Diagnosis and identification of vitamin D-dependent rickets
According to the above clinical manifestations and laboratory results, the diagnosis is not difficult.
Mainly related to vitamin D refractory rickets should be differentiated, the disease has spasm and severe muscle weakness; low blood calcium; blood phosphorus is normal or increased; the physiological amount of active vitamin D3 treatment is good, and shows obvious dependence, while the former Clinical symptoms and laboratory tests and treatment effects differ from the disease for identification.
