bubble_chart Overview

A metabolic acidosis caused by congenital genetic defects and various secondary factors that impair the proximal renal tubule's reabsorption of bicarbonate or/and the distal renal tubule's acid excretion function. It is classified into four types based on different clinical manifestations and divided into complete and incomplete forms according to severity. The most common type is complete distal renal tubular acidosis (complete type I renal tubular acidosis).

bubble_chart Diagnosis

I. Medical History and Symptoms

(1) More common in women aged 20-40. Some patients may have a history of chronic pyelonephritis, long-term use of analgesics, antibiotics, or cottonseed oil; others may have diffuse liver diseases, systemic diseases, or congenital or acquired kidney diseases.

(2) Most patients exhibit symptoms such as polydipsia, polyuria, increased nocturia, emaciation, and weight loss.

(3) The majority experience skeletal muscle weakness, particularly in the lower limbs, with some presenting periodic paralysis-like symptoms or even respiratory muscle paralysis.

(4) Frequent joint and bone pain, as well as generalized soreness.

(5) A few patients may experience deafness, sudden fractures, renal colicky pain with hematuria, or loose teeth.

(6) Symptoms of the primary disease may be present.

II. Physical Examination Findings

(1) Most patients appear emaciated, with rough and dry skin. Adolescents may show growth and developmental disorders.

(2) Some exhibit deformities in the lower limbs, muscle atrophy, functional impairment, tenderness at fracture sites or pelvic compression, and loose teeth.

(3) Physiological tendon reflexes are weakened or absent, with significantly reduced muscle strength.

(4) Signs of the primary disease may be present.

III. Auxiliary Examinations

(1) Varying degrees of hypokalemia, hyponatremia, hypocalcemia, hyperchloremia, and low bicarbonate levels, with low blood pH and urine pH typically above 5.5.

(2) Acid-loading tests (e.g., ammonium chloride loading test, urine pCO2 measurement, sodium sulfate loading test) yield positive results if urine pH exceeds 5.5.

(3) Urinalysis often shows mild changes or is normal. Changes may appear if the primary disease or other kidney pathologies are present.

(4) Blood BUN and Cr are mostly normal or show grade I elevation.

(5) B-ultrasound findings vary depending on the condition, with some showing kidney stones or calcifications, while others appear normal.

(6) Blood gas analysis primarily indicates metabolic acidosis, possibly accompanied by compensatory respiratory alkalosis.

(7) X-ray skeletal examination: Significant osteoporosis and softening, especially in the lower limbs and pelvis. Some may show fractures. Bone scintigraphy may reveal sparse and uneven isotope uptake.

IV. Differential Diagnosis

Should be distinguished from periodic paralysis, diabetes insipidus, diabetes mellitus, wind-dampness and rheumatoid arthritis, and decompensated renal insufficiency.

bubble_chart Treatment Measures

1. Eliminate aggravating factors, such as obvious diuresis and nephrotoxic drugs. Stones or accompanying urinary tract obstruction should be treated as early as possible.

2. Potassium supplementation: Potassium citrate is commonly used orally, usually 20ml, 3 times a day. The dosage varies depending on blood potassium levels and requires long-term maintenance. However, oral potassium chloride should not be used. Only when severe hypokalemia causes life-threatening arrhythmias should potassium chloride be administered intravenously until blood potassium reaches 3.5mmol/L, then immediately discontinued.

3. Correct metabolic acidosis: Administered simultaneously with potassium supplementation. The dosage of oral or intravenous sodium bicarbonate depends on blood bicarbonate levels, respiratory compensatory capacity, and blood pH. For mild cases, use 1.0, 3 times a day. Alternatively, long-term oral administration of sodium citrate mixture, 10–20ml, 3 times a day.

4. Correct osteoporosis: Long-term oral administration of vitamin AD pills, α-D3 0.5μg, once daily, combined with calcium supplements. Regular monitoring of blood calcium levels is necessary to prevent hypercalcemia. Nandrolone phenylpropionate can also be injected intramuscularly to promote bone growth.

5. Chinese medicine: Chinese medicinals can be applied based on pattern identification of kidney yin deficiency or kidney yang deficiency, such as Six-Ingredient Rehmannia Pill, Golden Chamber Kidney Qi Pill, or Rehmannia Pill. {|104|}