Pediatric idiopathic hypercalciuria

Introduction to children with idiopathic urinary calcium Idiopathic hypercalcemia (IH) is a disease in which the cause of urinary calcium is not fully understood and blood calcium is normal. Female urinary calcium is >6.2mmol (250mg/24h urine), and male urinary calcium is >7.5mmol (300mg/). 24h urine), often accompanied by hematuria and urinary calculi. basic knowledge Sickness ratio: 0.0001% Susceptible people: children Mode of infection: non-infectious Complications: urinary tract infection, obstructive nephropathy, hyperparathyroidism

The cause of idiopathic urinary hypercalcemia in children

(1) Causes of the disease

1. There are three possible causes of the cause, which may be due to increased intestinal urinary calcium absorption; renal tubular reabsorption of calcium dysfunction leads to increased urinary calcium; intestinal and renal tubules have dysfunction,

2. Classification of primary hypercalciuria, the cause is unknown, found in the pediatric population 2.2% ~ 6.2% asymptomatic IH, according to the pathogenesis can be divided into absorption and renal leakage type, in short, the mechanism of the disease May be caused by vitamin D metabolic disorders, and has a distinct familial genetic predisposition, which is autosomal dominant, and dietary and environmental factors are also associated with the disease.

(two) pathogenesis

1. Intestinal calcium absorption hyperthyroidism (absorption type) Mainly due to excessive absorption of calcium by the jejunum, causing a temporary increase in blood calcium to increase glomerular filtration calcium; inhibition of parathyroid secretion reduces renal tubular reabsorption of calcium; urine Calcium excretion increases and blood calcium can maintain normal. This type of mechanism is unknown. Some people think that vitamin D is a disorder.

2. Excessive calcium leakage from the kidney (kidney leakage type) Because the renal tubules cause excessive calcium leakage due to calcium reabsorption defects, stimulate the secretion of parathyroid glands, and the synthesis of 1,25-(OH)2D3 increases, causing intestinal calcium absorption to increase. Maintain normal blood calcium.

Prevention of idiopathic urinary calcium in children

The disease has obvious familial genetic predisposition, which is autosomal dominant inheritance. Preventive measures should be carried out from pre-pregnancy to prenatal. Pre-marital physical examination plays an active role in preventing birth defects. The size depends on the examination items and contents, including serum. Examination (such as hepatitis B virus, Treponema pallidum, HIV), reproductive system examination (such as screening for cervical inflammation), general physical examination (such as blood pressure, electrocardiogram), and asking about the family history of the disease, personal medical history and family history, etc. Consultation work, pregnant women should avoid harmful factors as much as possible, including away from smoke, alcohol, drugs, radiation, pesticides, noise, volatile harmful gases, toxic and harmful heavy metals, etc., in the process of antenatal care during pregnancy, systemic birth defects are required. Screening, including regular ultrasound examination, serological screening, etc., if necessary, chromosomal examination, if abnormal results occur, it is necessary to determine whether to terminate the pregnancy; the safety of the fetus in the uterus; whether there is sequelae after birth, whether it can be Treatment, prognosis, etc., take practical treatment measures, this disease Disease can also be caused by vitamin D metabolism, and diet, environmental factors, and should therefore be promoted reasonable method of feeding, more than the sun, to prevent and treat nutritional diseases.

Complications of pediatric idiopathic urinary calcium Complications, urinary tract infection, obstructive nephropathy, hyperparathyroidism

Often complicated by urinary tract infections, can develop into obstructive nephropathy, secondary hyperparathyroidism, nutritional disorders and so on.

Symptoms of pediatric idiopathic urinary hypercalcemia common symptoms polydipsia polyuria urinary calculi urinary calcium increased blood urinary urinary frequency parathyroid hyperthyroidism leukocytosis dysuria

More hematuria and urinary tract stones, polydipsia, polydipsia, polyuria, urine sedimentation, white, a few can develop chronic renal failure.

1. Hematuria and hematuria is the most common manifestation of IH in children. It can be gross hematuria or microscopic hematuria. It is found in all age groups. Stapleton reported that 58 cases of IH are accompanied by hematuria, 64% of which are gross hematuria, and hematuria can be transient. Sustained, the reason is mostly due to calcium crystallization caused by urinary tract injury, this hematuria belongs to normal red blood cell morphology hematuria (ie non-glomerular hematuria).

2. Urinary calculi adult IH showed urinary stones significantly higher than children, it has been reported that adult urolithiasis with IH up to 40% to 60%, while only 2% to 5% of pediatric urinary stones are caused by IH, According to the 58 cases reported by Stapleton, only 9 cases (16%) were associated with stones. These stones were mostly formed by calcium oxalate or calcium phosphate. The age of the stones was earlier than that of non-IH. If they were not treated, they could develop obstructive nephropathy. Cause the doctor to pay attention.

3. Other manifestations In addition to hematuria, there may be symptoms of bladder irritation (frequent urination, urgency, dysuria), dysuria syndrome, proteinuria, abdominal pain, low back pain and enuresis, etc. Easy urinary tract infection is a common clinical manifestation of IH. Because calcium is lost from the urine, the body's calcium is negatively balanced. A small number of patients may have secondary hyperparathyroidism, sparse bones, and a few patients show short stature, weight loss, muscle weakness and other symptoms.

Examination of children with idiopathic urinary calcium

1. Urinary examination increased urinary calcium, 24h urinary calcium>0.1mmol/kg (>4mg/kg), Uca/Ucr>0.21; hematuria, combined with infection, urine test leukocytosis, may have mild proteinuria, no tubular urine, visible Calcium oxalate, phosphate crystal; impaired urine concentration.

2. Blood test blood calcium is normal, blood phosphorus can be reduced, alkaline phosphatase is increased, serum parathyroid hormone concentration is increased, routine B-ultrasound, X-ray film, intravenous urography or CT examination, can find urinary tract Stones and other lesions.

Diagnosis and differentiation of children with idiopathic urinary calcium

diagnosis

1. Clinical characteristics For patients with unexplained simple hematuria, the history of family urinary stones should be asked to help diagnosis. For patients with clinical manifestations of urinary tract infection and urinary calculi, 24h urine should be collected for urine calcium (Uca) and Urinary creatinine (Ucr); if urinary calcium >0.1mmol/(kg·d) [>4mg/(kg·d)], the ratio of Uca/Ucr should be determined. If the ratio is >0.21, the disease can be initially diagnosed.

2. Urine test features urinalysis can have microscopic hematuria, leukocytosis, no proteinuria or only mild, no tubular urine, calcium oxalate and / or phosphate crystals can be seen, urine pH determination helps identify and analyze urinary crystals The nature of children can be impaired in urine concentration.

3. Other conditions for examination can be used as a calcium load test to identify whether it is an absorption type or a renal leakage type. In recent years, some authors believe that the oral calcium load test does not contribute to the expected nephrolithiasis. It is not recommended to use this test as a child with hypercalciuria. Routine diagnostic assessment, unless the serum parathyroid hormone concentration is elevated, another author suggests using the calcium-restricted and venous calcium tolerance test analysis to confirm the disease.

Differential diagnosis

According to the above clinical features, it is necessary to identify other causes of hypercalciuria and kidney stones, which can be diagnosed. The main identified diseases are: kidney stones caused by other causes, primary hyperparathyroidism, renal tubular Acidosis, etc., in addition, should also be differentiated from other diseases that cause increased urinary calcium, such as medullary sponge kidney, sarcoidosis, long-term cortisol treatment, Paget disease, chronic sepsis, sputum poisoning, Wilson disease, etc., according to Identification of various primary disease characteristics, in addition to the identification of intestinal absorption of calcium, renal tubular reabsorption of calcium dysfunction and the identification of urinary calcium increased by primary hyperparathyroidism, Pak (1975) proposed a A simple test to identify the method is: after 1 week of low-calcium diet, until 9:00 pm on the 6th day, drink 300ml of distilled water and fast, and drink 600ml of distilled water on the 7th day, collect 2h from 7:00 to 9:00 Urine, urine calcium, urine creatinine and urine cAMP, 9:00 blood to measure blood calcium, such as intestinal absorption of calcium increased, urinary calcium decreased or normal, urine cAMP normal or lower than normal, and renal tubular reabsorption of calcium Obstruction or primary parathyroid function In patients, urinary calcium increased, urine cAMP was higher than normal, and then the patient was given a calcium tolerance test (calcium 15mg/kg), intravenously infused, collected urine from 9:00 to 13:00 for 4 hours, and urine calcium was measured. Creatinine and urinary cAMP, such as intestinal absorption of calcium increased, urinary calcium increased significantly, urinary cAMP normal or lower than normal; primary hyperparathyroidism patients, increased urinary calcium, increased urinary cAMP, renal tubular reabsorption of calcium function In patients with dysfunction, urinary calcium increased significantly, while urinary cAMP decreased to normal, because calcium load inhibited secondary hyperparathyroidism, decreased PTH secretion, decreased urinary cAMP, and 30% of urinary cAMP was derived from renal tubular cells. The rest is from plasma, and the determination of urinary cAMP can indirectly demonstrate PTH levels.

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