Why is there less urine in children?

If parents find that their children urinate less, they must pay more attention and observe. This is definitely not a normal phenomenon, because children urinate more frequently. If it suddenly decreases, it must be caused by pathological reasons. Nowadays, there are many diseases that will cause this kind of precursor reaction, and even in severe cases, it will directly cause the patient to go into shock.

(1) Insufficient blood volume: It starts with functional oliguria and anuria. Once the blood volume is replenished, the urine volume will recover immediately. If it is not diagnosed and treated in time, it may cause organic kidney damage. Acute renal failure, manifested by oliguria or anuria, is seen in severe dehydration, massive bleeding, extensive burns, etc.

(2) Shock: Shock due to various reasons causes a decrease in renal perfusion pressure and a serious deficiency in glomerular filtration rate, which is seen in anaphylactic shock, hemorrhagic shock, cardiogenic shock, infectious toxic shock, etc.

(3) Decreased cardiac output: At this time, the blood supply to the kidneys decreases significantly, which is seen in left heart failure, severe arrhythmias, cardiac tamponade and constrictive pericarditis.

(4) Hepatorenal syndrome: In the late stage of cirrhosis, there is severe ascites and severe renal hypoperfusion, which manifests as oliguria or anuria. Once the ascites from cirrhosis is relieved, the kidneys will recover and the urine volume will increase. In hepatorenal syndrome, pathological examination of the kidneys is normal.

2. Renal oliguria and anuria

(1) Renal parenchymal damage: Whether it is primary glomerulonephritis or secondary to systemic lupus erythematosus, polyarteritis nodosa, infective endocarditis, dermatomyositis, etc., it can cause renal parenchymal damage and even renal function damage or failure, resulting in oliguria and anuria.

In the late stage of chronic renal failure, the kidneys atrophy, the glomerular filtration rate decreases, and the urine volume may be significantly reduced or even anuria; in the oliguria and anuria stage of acute renal failure, the symptoms are oliguria and anuria.

(2) Renal interstitial disease: The most common drug allergies such as penicillin, sulfonamides, rifampicin, aminoglycosides, etc. cause renal interstitial damage. It is also seen in the late stage of renal damage in chronic pyelonephritis.

Acute pyelonephritis is seen in renal papillary necrosis.

Heavy metal salt poisoning is seen in poisoning by mercury, lead, arsenic, gold, etc.

(3) Renal vascular diseases: renal cortical vasospasm or embolism, reduced renal blood supply leading to oliguria or anuria, seen in disseminated intravascular coagulation (DIC), pregnancy-induced hypertension syndrome, large-area burns, etc.