Renal tubular acidification dysfunction

Introduction Renal tubular acidification dysfunction is similar to type II renal tubular acidosis. Renal tubular acidosis leads to renal tubular acidosis. Proximal renal tubular acidosis (PRTA), also known as type II renal tubular acidosis, is characterized by: 1 When the concentration of bicarbonate (HCO-3) in the blood is normal, most of the glomerular filtered HCO-3 is discharged. HCO-3 reabsorption is reduced. 2 When the concentration of HCO-3 in the blood drops below the renal threshold of the patient's HCO-3, there is little HCO-3 in the urine. 3 In severe metabolic acidosis, the pH of the urine can be reduced to a minimum of 5.5, and the titratable acid and ammonium can be discharged.

Cause

Can be divided into primary and secondary. 1 primary also known as idiopathic proximal renal tubular acidosis. There is a family history, more common in women, there is no gender difference in sporadic cases. 2 Secondary may be part of Fanconi syndrome, or secondary to certain metabolic diseases such as cystitis, galactosemia, hepatolenticular degeneration, Lowe syndrome, vitamin D metabolic disorders and drug poisoning Etc. (acetazolamide, heavy metal lead, cadmium) can also be secondary to hyperparathyroidism and hyperimmune globulinemia.

Primary proximal renal tubular acidosis is caused by a congenital defect in HCO-3 reabsorption of the proximal tubule.

When the proximal renal tubular HCO-3 reabsorption defect, the plasma HCO-3 concentration is normal, and the HCO-3 in the filtrate is reduced in the proximal renal tubular reabsorption, most of which flows into the distal nephron, and the H+ secreted by the renal tubule is mostly used. Titration of HCO-3 reduces the acid excretion in the urine and increases the pH of the urine. Due to the decrease in proximal HCO-3 reabsorption, the concentration of plasma HCO-3 is reduced, which is one of the causes of acidosis. However, when the concentration of HCO-3 in the blood is lowered below the reabsorption capacity of the distal kidney unit, the HCO-3 in the tubule fluid can be completely reabsorbed by the distal kidney unit, and no HCO-3 is excreted in the urine. Because the distal uric acid function is normal, the urine pH can be lower than normal (urine pH 5.5).

Reduced Na+ and water reabsorption during proximal renal tubular acidosis, decreased extracellular fluid volume, stimulated secretion and activity of renin-angiotensin-aldosterone system, promoted Na+-K+ exchange, increased urinary potassium excretion, and potassium reduce.

Most renal tubular calcification does not occur with renal calcification, kidney stones and rickets. The true mechanism by which PRTA produces high chloride acidosis is unclear and may be related to increased reabsorption of Na+ and Cl-.

The growth of children with PRTA may be related to acidosis. There is evidence that the secretion of hGH is reduced during acidosis. Acidosis can also affect the synthesis of collagen. It may be due to various factors affecting growth. When high-chlorine acidosis is corrected, it grows. Back to normal.

an examination

Related inspection

Urine co2 determination urine dilution test uric acid renal tubular ammonia hippuric acid maximum excretion test HCO3-reabsorption test

Secondary diagnosis should be excluded when diagnosing PRAT, and urine routine, urine sugar, renal function, and amino acids should be measured to exclude PRTA caused by certain metabolic diseases.

Most cases of primary PRTA have a family history of women, and symptoms often begin within a year and a half after birth. In addition to slow growth, there may be symptoms of acidosis such as nausea, vomiting, anorexia and fatigue. Muscle weakness, constipation, and dehydration symptoms can also occur. There is generally no bone change and no renal calcification. Patients with hereditary diseases such as Fanconi syndrome, cystosic acidosis, hepatolenticular degeneration or galactosemia may have their primary symptoms.

Differential diagnosis

Attention should be paid to the identification of: 1 primary Fanconi syndrome; 2 cystineuria; 3 hepatolenticular degeneration; 4 secondary RTA caused by poison or drug poisoning.

Primary Fanconi Syndrome: Fanconi syndrome is a proximal tubular complex deficit disorder. Most cases of children are hereditary diseases. Most of the adult cases are acquired diseases. The latter are often secondary to chronic interstitial nephritis, Sjogren's syndrome, transplanted kidney, and heavy metal (mercury, lead, cadmium, etc.) kidney damage.

Hepatolenticular degeneration: Hepatolenticular degeneration, also known as Wilson disease, was first reported by Wilson in 1911. This is an autosomal recessive hereditary disease, more common in adolescents, congenital copper. Metabolic disorders. Clinically, liver damage, extrapyramidal symptoms and corneal pigment ring are the main manifestations.

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