Nephrology

Proteinuria does not necessarily imply kidney disease. It refers to an excess of proteins in urine, possibly caused by multiple factors: 

• Temporary causes: conditions such as strenuous exercise, fever, and pregnancy can lead to transient proteinuria.
• Benign conditions: physiological proteinuria, which is more common in youths.
• Kidney disease: persistent proteinuria possibly due to kidney problems, e.g. conditions in the renal tubes and renal glomerulus. 

To confirm a kidney disease diagnosis, a comprehensive assessment is required based on the presence of proteinuria PLUS other clinical symptoms, examination results and a patient’s medical history. Please consult your doctor for further examination if you have symptoms or persistent proteinuria.

Loin pain most likely occurs in renal conditions such as acute pyelonephritis, kidney stones or kidney tumours. Mostly, back pain is associated with the muscles and bones, but might be caused by something other than a sprained back or other related problems. If abnormal symptoms occur, do not take them lightly and consult a doctor immediately.

Symptoms may vary with the severity and type of kidney condition. The most common include:

• Oedema: swelling in the ankles, legs or around the eyes.
• Changes in urine: an increase or decrease in urine volume; foamy urine; darker or lighter urine (possibly bloody urine).
• High blood pressure due to impaired renal function.
• Fatigue: feeling extremely tired or weak, possibly due to anaemia caused by poor renal function.
• Poor appetite: no interest in eating or nausea.
• Skin changes: dry skin, itchiness or rash.
• Loin pain, especially in the kidney area. 

Please consult a doctor for further examination and diagnosis as soon as you have the above symptoms.

Based on the extent of kidney damage, i.e. glomerular filtration rate (GFR), kidney disease generally has five stages: 

1. GFR ≥ 90 mL/min: kidney functions normally or there is mild damage, possibly indicative of kidney disease (e.g. proteinuria or haematuria, i.e. blood in urine).
2. GFR 60-89 mL/min: the kidneys have mild damage, usually presented with no obvious symptoms.
3. GFR 30-59 mL/min: the kidneys have medium damage with possible symptoms such as oedema or high blood pressure.
4. GFR 15-29 mL/min: the kidneys have severe damage with more apparent symptoms;
5. GFR < 15 mL/min: the kidneys have already failed and lost almost all functions; dialysis or a kidney transplant is required 

Depending on the stage of the kidney disease, doctors can determine the severity of the condition and formulate proper treatment plans.

The causes of chronic renal failure are varied. Common causes include:

• Diabetes: High blood sugar levels may cause damage to the glomerulus, resulting in diabetic nephropathy.
• Persistent high blood pressure exerts excessive pressure on the kidneys and affects renal function.
• Glomerular disease: GFR may decrease due to chronic problems or long-term damage to the renal tubules and glomeruli.
• Polycystic kidney disease: a genetic condition marked by the growth of cysts in kidneys and impact on renal functions.
• Obstructive uropathy: Urine flow is blocked due to kidney stones or prostatic hyperplasia, causing damage to the kidneys.
• Systemic diseases such as lupus erythematosus and rheumatoid arthritis may affect the kidneys.
• Long-term use of certain medications: NSAIDs and certain antibiotics may cause toxicity to the kidneys.
• Infection: repeated nephropathy（such as pyelonephritis）may cause chronic damage.
• Inappropriate use of herbs 

Each of these factors may cause a gradual loss of renal function on its own or with others. Early diagnosis and health management are thus crucial for protecting the kidneys.

Methods of renal assessment: 

• Serum creatinine test measures the level of creatinine in blood, a by-product of muscle metabolism often released by the kidneys. Rising creatinine levels indicate a loss of renal function.
• Estimated glomerular filtration rate (eGFR) using common formulas such as Cockcroft-Gaults and MDRD. The eGFR is calculated based on the level of creatinine in blood, as well as age, gender and weight, to assess the filtration function of the kidneys.
• Urine analysis to measure the amount of protein, red blood cells and white blood cells to assess kidney condition.
• Urine protein quantity to measure the amount of protein in urine. Persistent proteinuria may indicate kidney disease.
• True GFR (the most accurate) measures the serum creatinine levels in urine collected over a 24 hour period.
• Ultrasound is used to assess kidney size, shape and structure and to detect kidney stones, cysts or tumours. Other important radiological imaging studies include computerised tomography scan, magnetic resonance imaging and radionuclide scan.
• Renal biopsy: under specific circumstances, renal tissues are obtained by renal biopsy for diagnosis and assessment to give doctors a definite understanding of renal function and formulate treatment plans

Kidney disease has many complications. The common ones include the following: 

• High blood pressure due to kidney failure, which in turn can cause further damage to the kidneys.
• Anaemia possibly caused by reduced EPO production by the kidneys, causing fatigue and weakness.
• Skeletal problems: metabolic bone disease due to calcium and phosphorus imbalance.
• Cardiovascular disease: patients with kidney disease are at higher risk of developing heart disease and stroke.
• Gout due to high uric acid associated with chronic kidney failure
• Electrolyte imbalance such as hyperkalaemia may cause severe conditions such as arrhythmia.
• Uraemia: toxins accumulate in the body as renal function severely declines, possibly causing nausea, vomiting and confusion.
• Patients with kidney disease are at higher risk of infection due to a compromised immune system.
• Renal failure patients may reach end-stage renal disease without timely treatment and require dialysis or live transplant (i.e. transplant from a living donor).

 Early diagnosis and treatment are thus critical for reducing the risk of complications.