The short answer: Fractional excretion of sodium (FENa) is a urine-based calculation that estimates how much of the sodium filtered by the kidneys is ultimately excreted in urine. Traditionally, a FENa below 1% has suggested a prerenal cause of acute kidney injury (AKI), while a FENa above 2% has suggested intrinsic kidney injury, particularly acute … Read more
The short answer: A sudden rise in blood potassium can be important because potassium affects the electrical activity of the heart. However, the number alone does not tell the whole story. The speed of the rise, kidney function, medications, symptoms, ECG findings, and whether the result is genuine all matter. A high potassium result can … Read more
The short answer: Calcium and parathyroid hormone (PTH) are closely connected in kidney disease, but neither result should be interpreted by itself. As chronic kidney disease (CKD) progresses, the kidneys may have more difficulty removing phosphorus and activating vitamin D. This can disturb calcium balance and stimulate the parathyroid glands to produce more PTH. Over … Read more
The short answer: For most adults, a typical blood phosphorus range is about 2.5–4.5 mg/dL (0.81–1.45 mmol/L), although laboratory reference ranges can differ. In CKD, phosphorus can rise as kidney function declines because the kidneys become less able to remove excess phosphate. However, one mildly high phosphorus result does not by itself establish a serious … Read more
The short answer: Microalbuminuria is the older term for moderately increased albuminuria, usually a urine albumin-to-creatinine ratio (UACR) of 30–299 mg/g. In someone with diabetes, it can be an early sign that the kidneys are being affected. But one elevated urine test does not automatically mean permanent diabetic kidney disease. Albuminuria can fluctuate, and in … Read more
The short answer: Stage 4 chronic kidney disease (CKD) means severely reduced kidney function, usually with an eGFR of 15–29 mL/min/1.73 m² that has persisted for at least 3 months. Symptoms can become more noticeable at this stage, but there is no reliable symptom-by-symptom timeline leading from Stage 4 to Stage 5. Some people remain … Read more
The short answer: Cystatin C is a blood marker that can help estimate how well your kidneys filter blood. It is often useful when creatinine may give a less reliable picture of kidney function—for example, in people with unusually low or high muscle mass. However, cystatin C is not automatically better than creatinine for everyone. … Read more
The short answer: A small drop in eGFR after starting certain blood pressure medicines can be an expected effect rather than permanent kidney damage. This is especially true with ACE inhibitors and ARBs, which change pressure inside the kidney’s filtering units. However, a substantial or continuing decline in kidney function needs evaluation, particularly if creatinine … Read more
The short answer: Protein or albumin detected on a urine dipstick means that more protein than expected was detected in the urine sample. It can be an early sign of kidney disease, but one positive dipstick does not automatically mean you have CKD. Dehydration, intense exercise, fever, infection, and other temporary conditions can also affect … Read more
The short answer: The BUN-to-creatinine ratio compares two blood tests: blood urea nitrogen (BUN), which reflects urea in the blood, and creatinine, a waste product cleared mainly by the kidneys. A high ratio can occur when blood flow to the kidneys is reduced, such as with dehydration, but it can also rise with gastrointestinal bleeding, … Read more