Proximal (type II) renal tubular acidosis
Introduction
Introduction of proximal (type II) renal tubular acidosis Renal tubular acidosis (RTA) is a metabolic acidosis caused by congenital genetic defects and various secondary factors leading to proximal tubular resorption of sodium bicarbonate or/and distal renal tubular dysfunction. The primary cause is unknown and is generally considered to be related to heredity. Only manifested as HCO3-reabsorption disorder, without other renal tubular and glomerular dysfunction. Secondary often secondary to systemic disease, can be associated with a variety of renal tubular dysfunction, Fanconi (Fanconi) syndrome is the most common. basic knowledge The proportion of sickness: 0.01% Susceptible people: family history, more common in women Mode of transmission: mother-to-child transmission Complications: proteinuria
Cause
Proximal (type II) cause of renal tubular acidosis
Primary
The cause is unknown and is generally considered to be related to heredity. Only manifested as HCO3-reabsorption disorder, without other renal tubular and glomerular dysfunction. 1 sporadic, the baby is temporary. 2 hereditary, persistent, autosomal dominant or autosomal recessive.
2. Secondary
Often secondary to systemic disease, can be associated with a variety of renal tubular dysfunction, Fanconi (Fanconi) syndrome is the most common.
(1) Hereditary diseases with other genetic diseases associated with other proximal tubular dysfunction, such as idiopathic Fanconi syndrome, cystine disease, ocular-brain-renal syndrome (Lowe syndrome), heredity Sexual fructose intolerance, tyrosinemia, galactosemia, glycogen storage disease, and the like.
(2) Drug and toxin kidney damage such as carbonic anhydrase inhibitor, methyl 3-chromone, maleic acid poisoning, heavy metal (calcium, lead, copper, mercury) poisoning.
(3) Others such as subacute necrotizing encephalomyelopathy (Leigh syndrome), tetralogy of Fallot, intestinal malabsorption, hyperparathyroidism, hereditary nephritis, chronic rejection of renal transplantation, multiple myeloma, starch Degeneration, chronic active hepatitis, renal medullary cystic disease, Wilson's disease, etc.
Prevention
Proximal (type II) prevention of renal tubular acidosis
Active treatment of primary disease and complications, such as the occurrence of bone disease or severe calcium deficiency can give calcium and active vitamin D preparations.
Complication
Proximal (type II) renal tubular acidosis complications Complications
May have mental retardation, obvious hypophosphatemia and complications such as diabetes, amino aciduria, proteinuria and so on.
Symptom
Proximal (type II) symptoms of renal tubular acidosis Common symptoms Uric acid abnormalities nausea and vomiting Loss of appetite and urinary bone pain "Duck step" gait kidney stone kidney calcification kidney area dull pain fatigue
In the proximal renal tubular acidosis, the blood chlorine increased>100106mmol/L, the blood pH<7.35, the blood potassium and HCO-3 were lower than normal, and the HCO-3 in the urine increased under normal conditions. The severe acidosis plasma HCO When the concentration of -3 is low, the urinary excretion of HCO-3 is rarely or completely absorbed. When HCO-3 is discharged to 0, the urine pH is lowered, the patient's kidney HCO-3 threshold is lower than normal, and the ammonium chloride load test urine pH can be gradually reduced to 5.5, can be used for one-time ammonium chloride load test: NH4Cl 0.1g/kg, after taking the service, collect urine for 2-8 hours, urinate once every hour, measure urine pH.
Method for measuring renal HCO-3 threshold: Threshold of renal tubular reabsorption of HCO-3 refers to the lowest concentration of plasma HCO-3 in the presence of HCO-3 in urine by administering a sufficient amount of NaHCO3 to plasma HCO-3. After the concentration is normal (25mmol/L), the plasma HCO-3 will gradually decrease. The blood is measured daily for HCO-3 creatinine and HCO-3 in urine; creatinine and urine pH is 1-2 times, or 5% NaHCO3500ml, Intravenously drip at a rate of 4 ml/min, urinating once every 30 to 60 minutes, taking blood and urine and HCO-3 and creatinine concentrations, measuring urine pH, when urine HCO-3 is fully absorbed, urine pH When the concentration is reduced to 5.5-6.0, the concentration of HCO-3 in the blood is the threshold of renal HCO-3. The normal human kidney HCO-3 threshold is 21-22 mmol/L for infants within 1 year old, and 22-24 mmol/L for children. The patient was lower than normal, and the glomerular filtration rate (GFR) was calculated using blood and urine creatinine. The reabsorption rate and excretion fraction of renal tubular HCO-3 were calculated by the following formula. The plasma HCO-3 was used in children with PRTA. When the concentration is normal, the maximum excretion fraction of renal HCO-3 is often >15%, and the reabsorption rate of HCO-3 is decreased.
Examine
Proximal (type II) examination of renal tubular acidosis
1, blood biochemical examination: 1 blood pH value, HC03 - or cch binding force decreased; 2 blood chlorine is significantly increased, blood potassium is significantly reduced, anion gap can be normal.
2, urine examination: 1 urine specific gravity and osmotic pressure decreased; 2 urine PH> 6, when acidosis increased, blood HCO3 - <16mmol / L, urine PH <5.5.
3, HC03 - excretion score (FEHC03 -) > 15%.
4, ammonium chloride load test: urine pH value <5.5.
Diagnosis
Diagnosis and identification of proximal (type II) renal tubular acidosis
diagnosis
PRAT should exclude secondary causes, urine routine, urine sugar, kidney function and amino acids, etc., in order to exclude PRTA caused by certain metabolic diseases. For details, see the relevant section. Most cases of family history of primary PRTA are female. Symptoms often start within one and a half years after birth. In addition to slow growth, there may be symptoms of acidosis such as nausea, vomiting, anorexia and fatigue, etc., muscle weakness, constipation, dehydration symptoms, and generally no bone changes. Renal calcification does not occur in patients with hereditary diseases such as Fanconi syndrome, cystosic acidosis, hepatolenticular degeneration or galactosemia, and may have its primary symptoms.
Differential diagnosis
Must pay attention to the identification of the following diseases:
1 primary Fanconi syndrome;
2 cystine urine;
3 hepatolenticular degeneration;
4 secondary RTA caused by poison or drug poisoning.
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