Signals of Unhealthy or Morbid State of Kidneys
Chronic kidney disease (CKD) is diagnosed by the persistent presence of elevated urinary albumin excretion (albuminuria), low estimated glomerular filtration rate (eGFR), or other manifestations of kidney damage that persist for more than 3 months. 1
Key Diagnostic Markers of Kidney Dysfunction
Laboratory Abnormalities
Glomerular Filtration Rate (GFR) Abnormalities
Albuminuria/Proteinuria
Electrolyte and Acid-Base Disturbances 1, 3
- Hyperkalemia (elevated potassium)
- Hyperphosphatemia (elevated phosphate)
- Hypocalcemia (low calcium)
- Metabolic acidosis (bicarbonate deficiency)
- Hyponatremia or hypernatremia (depending on fluid status)
- Hypomagnesemia (in advanced stages)
Urinary Abnormalities
- Hematuria (blood in urine) 1
- Pyuria (white blood cells in urine) 1
- Abnormal urinary sediment (cellular casts) 1
- Reduced urine output (<0.5 mL/kg/hr for >6 hours) 1
Imaging Findings
- Abnormal kidney structure on ultrasound or other imaging 1
- Changes in kidney size (enlarged or shrunken)
- Presence of cysts, masses, or hydronephrosis
CKD Staging and Classification
CKD is classified based on cause, GFR category, and albuminuria category 2:
| CKD Stage | GFR (mL/min/1.73m²) | Description |
|---|---|---|
| G1 | ≥90 | Normal or high GFR with evidence of kidney damage |
| G2 | 60-89 | Mildly decreased GFR with evidence of kidney damage |
| G3a | 45-59 | Mildly to moderately decreased GFR |
| G3b | 30-44 | Moderately to severely decreased GFR |
| G4 | 15-29 | Severely decreased GFR |
| G5 | <15 | Kidney failure |
Clinical Manifestations of Kidney Dysfunction
Early Signs (Often Asymptomatic)
- Hypertension (often the earliest clinical sign) 4
- Mild edema (fluid retention)
- Nocturia (increased nighttime urination)
- Foamy urine (suggesting proteinuria)
Advanced Signs and Symptoms
Uremic syndrome (when GFR falls significantly) 1
- Fatigue and weakness
- Nausea and vomiting
- Anorexia (loss of appetite)
- Pruritus (itching)
- Cognitive changes and confusion
- Muscle cramps and twitching
- Sleep disturbances
Volume overload manifestations 1, 5
- Peripheral edema
- Pulmonary edema
- Hypertension resistant to treatment
- Shortness of breath
Anemia-related symptoms 2
- Fatigue
- Weakness
- Reduced exercise tolerance
Complications Indicating Advanced Kidney Disease
- Metabolic bone disease (renal osteodystrophy) 1
- Secondary hyperparathyroidism 5
- Cardiovascular complications 6
- Malnutrition and protein-energy wasting (especially in dialysis patients) 1
- Immune dysfunction with increased susceptibility to infections 1
Important Considerations for Detection
- CKD is often asymptomatic until advanced stages 6
- Less than 5% of patients with early CKD are aware of their disease 6
- Diabetes and hypertension are the most common causes of CKD in developed countries 6
- Acute kidney injury (AKI) can progress to chronic kidney disease if not properly managed 1
- Certain medications can cause or worsen kidney dysfunction (NSAIDs, nephrotoxic antibiotics, contrast dye) 1
Pitfalls in Kidney Function Assessment
- Serum creatinine alone is an inadequate marker, especially in elderly or those with reduced muscle mass 7
- Creatinine clearance decreases by approximately 1 mL/min/year after age 40 7
- Rapid changes in kidney function may indicate acute kidney injury rather than chronic disease 1
- Albuminuria can be transiently elevated due to exercise, infection, fever, heart failure, or marked hyperglycemia 1
Early detection of these signals is crucial as CKD is associated with increased risks of cardiovascular disease, progression to kidney failure requiring dialysis or transplantation, and increased mortality 1, 6.