Why it is performed
- Detect or monitor kidney disease.
- Support safe dosing of certain medicines.
- Assess dehydration, electrolyte imbalance or metabolic risk.
- Measure albuminuria, an early marker of kidney damage in diabetes and hypertension.
How it is performed
Creatinine is measured in blood and used with age and sex to estimate glomerular filtration. Urine may add albumin, protein, sediment or clearance information depending on the clinical question.
Preparation
- Keep your usual hydration unless instructed otherwise.
- Avoid very intense muscle exercise and large amounts of cooked meat before creatinine if advised.
- For 24-hour urine, follow start and finish times exactly and collect the entire volume.
- Report creatine, supplements and medicines.
How Askabide processes it
At Askabide
Available creatinine, urea and electrolytes are processed by dry chemistry. Estimated filtration is calculated using the laboratory’s adopted equation. Albuminuria and unavailable methods may be referred.
The main analytical phase is performed in the centre’s laboratory, subject to availability and validation.
Results and indicative intervals
Intervals vary by method, analyser, reagent, units, age, sex, pregnancy, menstrual-cycle phase and reference population. The valid interval is the one printed on the laboratory report.
| Parameter or result | Indicative reference | How it is interpreted |
|---|---|---|
| Creatinine | ≈0,6–1,3 mg/dL | There is no single useful interval without considering age, sex and muscle mass. |
| Estimated GFR | ≥90 mL/min/1,73 m² suele considerarse conservado | 60–89 does not by itself establish kidney disease; duration and other markers matter. |
| Urea / BUN | BUN 6–20 mg/dL | May increase with dehydration, high-protein intake, gastrointestinal bleeding or reduced kidney function. |
| Urine albumin/creatinine ratio | <30 mg/g habitualmente | 30–300 mg/g indicates moderately increased albuminuria; confirmation is needed because exercise, fever and infection affect it. |
| Potassium | 3,5–5,1 mmol/L | Extreme values may be urgent; haemolysis can cause a false increase. |
Important limitations
- eGFR is an estimate, not a direct measurement.
- Creatinine may look normal in people with low muscle mass despite reduced function.
- Chronic kidney disease generally requires persistent abnormalities for at least three months.
- A single albuminuria result may be transient.