The glomerulus filters 180 liters of fluid per day, about 99% of which is reabsorbed by the renal tubules, such as water, potassium, sodium, glucose, amino acids, uric acid, phosphate, bicarbonate and other substances needed by the body, damage to the tubules necrosis, diabetic nephropathy, etc. can cause tubular reabsorption dysfunction. The following diseases are the causes of renal tubular reabsorption disorders: 1. Hypercalcemic nephropathy Hypercalcemic nephropathy (hypercalcemic nephropathy) refers to the organic damage and functional changes of the kidney caused by hypercalcemia (serum calcium 2.8 mmol/L). The main manifestation is tubulointerstitial lesions. Renal concentration dysfunction is the most significant and earliest functional abnormalities of hypercalcemic nephropathy. 2, renal diabetes Renal glucosuria (renal glucosuria) is a disease in which the glucose concentration is normal or below the normal renal glucose threshold, due to reduced glucose reabsorption in the proximal tubule caused by diabetes. Clinically divided into primary renal diabetes and secondary renal diabetes. 3, primary aldosteronism primary aldosteronism (primary aldosteronism, referred to as primary aldosteronism), is due to adrenal cortical lesions and thus secrete too much aldosterone, resulting in water and sodium retention, increased blood volume, the activity of the renin-angiotensin system is inhibited, the clinical manifestations of hypertension, hypokalemia as the main features of the syndrome. Most of them are caused by adrenal aldosterone adenoma, and may also be idiopathic aldosteronism. 4, hepatomegaly Hepatomegaly is a hereditary disease mainly in adolescents, caused by disorders of copper metabolism. It is characterized by cirrhosis, softening and degeneration of the basal ganglia of the brain, and corneal pigment rings (Kayser-Fleischer rings), with plasma copper cyanine deficiency and amino aciduria. Also known as Wilson’s disease. 5, pediatric diabetic nephropathy Diabetic nephropathy is a common and multifocal complication of diabetes. Glomerulosclerosis due to microangiopathy caused by diabetes is one of the most serious complications and one of the leading causes of death due to diabetes. Diabetes mellitus is a common metabolic syndrome that manifests not only elevated blood glucose but also disorders of fat, protein, water and electrolyte metabolism. In the early stage of diabetes, the kidney volume increases, the glomerular filtration rate increases, and the kidney is in a hyperfiltration state. Later, interstitial proteinuria or microalbuminuria gradually appears, and with the prolongation of the disease, persistent proteinuria, edema, hypertension, reduced glomerular filtration rate, and then renal insufficiency and uremia occur. Because it is a late complication of diabetes mellitus, it is less common in the pediatric stage.