What Are the Symptoms of Acute Kidney Disease?

The kidney is an organ of metabolism in the human body. Acute kidney disease usually refers to acute nephritis, with common symptoms including changes in urine, proteinuria, edema, hypertension, and other systemic symptoms. It is necessary to seek medical attention promptly to avoid delaying treatment.

40% to 70% of patients with acute nephritis may experience gross hematuria, with urine appearing reddish or brownish in color, similar to washed meat water, red tea, or soy sauce. This condition usually persists for about two weeks before turning into microscopic hematuria. Microscopic hematuria mostly disappears within six months, but can also persist for 1 to 3 years before completely resolving. In the early stages of the disease, urine output is significantly reduced, and may even be absent (less than 100ml per day). If urine output remains absent for more than three days, it indicates a severe condition, often accompanied by azotemia, indicating damage to kidney function. During the recovery phase of the disease, urine output gradually increases, potentially reaching over 2000ml, and kidney function gradually returns to normal.

Almost all patients with acute nephritis experience proteinuria, manifesting as an increase in foam in the urine. The degree of proteinuria varies with the severity of the disease, and it often persists longer than other symptoms. Even after edema resolves, proteinuria may persist for 1 to 2 months or even longer before gradually resolving.

Edema is often the first symptom of acute nephritis, occurring in 70% to 90% of cases, with varying severity. In mild cases, only eyelid swelling is observed, but in severe cases, edema may extend to the entire body. Some patients may also experience symptoms such as pleural effusion and ascites. Edema typically begins to resolve within 2 to 3 weeks, and urine output gradually increases.

About 80% of patients with acute nephritis may have hypertension, with blood pressure usually moderately elevated. In adults, blood pressure is typically between 18.7 and 22.7 kPa/12.0 and 14.7 kPa. Occasionally, more severe cases may develop into hypertensive crisis, but diastolic blood pressure rarely exceeds 16 kPa. If blood pressure persists and does not decrease, it may be a precursor to chronic nephritis, indicating more severe kidney damage.

In addition to the above clinical manifestations, patients often experience systemic symptoms such as general discomfort, fatigue, low back pain, frequent urination, and anorexia. Some patients may also have prodromal infections such as sore throat, fever, and skin ulcers.