Diseases Easily Confused with Uremia

Uremia presents with symptoms such as loss of appetite, dulled senses, emotional apathy, excessive sleepiness, reduced urine output, facial and lower limb edema, anemia, itchy skin, muscle spasms, restlessness, and even seizures in severe cases. These symptoms may develop slowly, remaining hidden for long periods, or emerge rapidly within days in acute kidney failure. Uremia syndrome varies widely, and not all symptoms necessarily appear.

Diagnosis and Differential Diagnosis of Uremia

1. Blood Tests

• Elevated blood urea nitrogen (BUN) and creatinine levels.
• Hemoglobin typically below 80 g/L, dropping to 20–30 g/L in end-stage, often with reduced platelets or elevated white blood cells.
• Arterial blood gas and acid-base tests show late-stage pH decline, reduced actual bicarbonate (AB), standard bicarbonate (SB), base excess (BE), and compensatory PaCO2 decrease.
• Plasma protein levels may remain normal or decrease.
• Electrolyte imbalances may occur.

2. Urine Tests

• Urinalysis varies depending on the underlying cause, showing proteinuria, red or white blood cells, or casts, though changes may be subtle.
• Urine specific gravity often below 1.018, fixed at 1.010–1.012 in uremia, with nighttime urine volume exceeding daytime.

3. Kidney Function Tests

• Reduced glomerular filtration rate (GFR) and endogenous creatinine clearance.
• Impaired phenol red excretion and urine concentration-dilution tests.
• Abnormal free water clearance.
• Radionuclide renography, kidney scans, or scintigraphy aid in assessing kidney function.

4. Other Tests

• Plain X-rays or contrast imaging of the urinary system and kidney biopsy help identify underlying causes.

Diagnosis relies on a history of chronic kidney disease, clinical symptoms, and urine and blood biochemistry results. Kidney function impairment is classified into three stages based on GFR, BUN, and creatinine levels:

• Compensated Renal Insufficiency: GFR 50–70 mL/min, BUN 7.14–8.93 mmol/L, creatinine 132–177 µmol/L. Patients show primary disease symptoms but lack others.
• Decompensated Renal Insufficiency or Azotemia: GFR <50 mL/min, BUN >8.93 mmol/L, creatinine >177 µmol/L. Mild fatigue, reduced appetite, and varying anemia appear.
• Uremia Stage: GFR <25 mL/min, BUN >21.42 mmol/L, creatinine >442 µmol/L, with evident uremia symptoms. GFR <10 mL/min indicates late-stage uremia; GFR <5 mL/min marks end-stage uremia.

Once chronic kidney failure is confirmed, identifying the primary cause and aggravating factors is crucial for effective treatment.