Most patients reach a nephrology clinic later than they should have. Not because anyone was careless — because chronic kidney disease produces no symptoms until it is advanced, and the two tests that catch it early are easy to order and easy to forget.
By the time swelling, fatigue, or foamy urine push someone toward a specialist, a substantial share of kidney function is usually gone and is not coming back. Referred at the right point, the same person often has years of preserved function still available to them.
So here are the actual thresholds.
The two numbers
Kidney function is staged on two measurements, and you need both. Either one alone will mislead you.
eGFR — estimated glomerular filtration rate — is calculated from a serum creatinine level together with age and sex. It estimates how much blood the kidneys filter per minute. Above 90 is normal. 60 to 89 is mildly reduced. 45 to 59 and 30 to 44 are the moderate bands. 15 to 29 is severe. Below 15 is kidney failure.
uACR — urine albumin-to-creatinine ratio — measures protein leaking into the urine. Under 30 mg/g is normal. 30 to 300 is moderately increased. Above 300 is severely increased.
Why both: albuminuria frequently shows up years before eGFR starts to fall. A patient with an eGFR of 85 and a uACR of 400 has kidney disease and a meaningfully elevated risk of progression — and an eGFR-only workup will hand them a clean bill of health. The reverse error matters too. One low eGFR in someone who was dehydrated that morning is not chronic kidney disease. Chronicity requires the abnormality to persist for at least three months.
Current international guidance stages the disease on both axes simultaneously. That is why nephrologists talk about a grid rather than a number.
When referral is warranted
These are the situations where bringing in a specialist changes what happens next:
- eGFR persistently below 30. The clearest threshold there is. It is also the point at which planning for future treatment options has to start — well before anything is actually needed.
- uACR persistently above 300 mg/g , or any albuminuria accompanied by unexplained blood in the urine.
- A sustained decline in eGFR — a drop of 25 percent or more from baseline, or a steady downward slope across months, regardless of where the absolute number sits.
- Blood pressure above target on three medications , one of them a diuretic at an appropriate dose.
- Recurrent kidney stones , or a first stone in a young patient or someone with a strong family history.
- Persistent electrolyte abnormalities — potassium, sodium, calcium, or bicarbonate that keep drifting.
- Acute kidney injury that has not returned to baseline , or a second episode.
- A known genetic kidney condition , or a first-degree relative on dialysis or carrying a transplant.
Notice what is absent from that list: a single abnormal creatinine, and symptoms. Waiting for symptoms is precisely how patients arrive late.
What a first nephrology visit should produce
Not a prescription. A cause and a slope.
The visit has three questions to answer. Why are the kidneys injured — diabetes, hypertension, an immune process, obstruction, a medication, something inherited? How fast is it moving, established from prior labs rather than from today's single value? And what is modifiable — blood pressure control, glycemic control, urinary protein, over-the-counter anti-inflammatories, contrast exposure, or a drug that needs its dose corrected for kidney function.
Expect a urinalysis with microscopy, a quantified albumin measurement, a review of every lab going back as far as records allow, imaging in most cases, and a medication review more thorough than you are used to. Occasionally a biopsy is the only way to answer the "why," and that decision belongs at this visit rather than three appointments later.
The output is a staged plan with an interval attached to it.
Nephrologist or urologist
Patients get routed to the wrong one regularly, and the distinction is worth holding onto.
A nephrologist is an internal medicine physician with fellowship training in kidney function — filtration, blood pressure, electrolytes, acid-base balance, dialysis, and transplant medicine. The work is medical.
A urologist is a surgeon who operates on the urinary tract and the male reproductive system — obstruction, tumors, the plumbing.
Kidney stones are the overlap that causes most of the confusion. A stone that is obstructing and needs to come out is a urologic problem. Working out why you keep forming stones, and stopping the next one, is a nephrology problem. Patients with recurrent stones often need both, and the metabolic workup is the half that usually gets skipped.
Three things specific to kidney patients in this city
Heat. Repeated episodes of working or training to the point of dehydration in extreme heat cause measurable kidney injury, and the accumulation of those episodes is now an established mechanism for chronic kidney disease in outdoor workers worldwide. In a city with a long, punishing summer and a very large outdoor workforce, that is not a theoretical exposure. If you work outside and carry any risk factor at all, your kidney function belongs on a schedule.
Storms. Dialysis is the medical service most vulnerable to flooding and power loss, and this region has tested that repeatedly. Anyone on dialysis, or approaching it, should have a plan on file before hurricane season: a backup unit outside their usual flood corridor, a current copy of the dialysis prescription, the emergency diet, and the regional kidney emergency contact line. Arrange it in February, not in August.
The Medical Center. Houston's concentration of transplant programs is a real advantage, but evaluation carries a timeline of its own, and eligibility can be established long before dialysis begins. Transplantation performed preemptively — before dialysis starts — produces better outcomes than transplantation after. That timing is a decision made in a nephrology clinic, not at the transplant center.
Verifying credentials
Nephrology is a subspecialty of internal medicine, certified through the American Board of Internal Medicine. You can confirm any physician's certification status free through the American Board of Medical Specialties. The Texas Medical Board publishes license status, training history, and disciplinary record for every physician licensed in the state. The federal NPI registry confirms listed specialty and practice location.
All three take about two minutes combined. For a subspecialty this consequential, spend them.
What to bring
Every creatinine and eGFR result you can lay hands on, going back as far as possible — the trajectory tells us more than any single value. Any urine testing you have had. Your pill bottles, supplements and pain medications included. Home blood pressure readings, if you take them. The names of your other physicians. And if kidney disease runs in your family, what the diagnosis was.
One more thing. If you have diabetes, high blood pressure, or a family history of kidney disease and you have never had a urine albumin measured, that is the single most useful test to ask for before you come in.