A routine blood test comes back, and one number stands out: creatinine. Seeing it flagged as high can be worrying, especially when you’re not sure what it means. Sometimes a high result reflects something temporary, like dehydration. Other times, it’s an early sign that your kidneys need closer attention. Knowing the difference helps you understand who should guide your care and how doctors work together to protect kidney health and manage kidney disease when it’s present. This article explains what high creatinine means, why it matters, and when a kidney specialist may become part of your care.
What Is Creatinine?
Creatinine is a waste product your muscles make during normal daily activity. Healthy kidneys filter it out of your blood and send it out of your body in urine.
When your kidneys aren’t filtering well, creatinine builds up in the blood. That’s why doctors use it as a basic measure of kidney function. Normal ranges vary by lab, age, sex, and muscle mass. For many adults, the normal range falls roughly between 0.6 and 1.3 mg/dL.
Doctors also use your creatinine level to estimate your glomerular filtration rate, or eGFR. This number shows how well your kidneys clean your blood. An eGFR of 60 or higher is usually considered normal.
Why High Creatinine Matters
A high creatinine level doesn’t always mean kidney disease. Several everyday factors can raise it for a short time:
- Dehydration
- Intense exercise
- Eating a large amount of meat before the test
- Creatine supplements
- Certain medications
When levels stay high over time, though, they may point to reduced kidney function. Common causes include diabetes, high blood pressure, urinary blockages, and some long-term medication use. Kidney disease often has no symptoms in its early stages, so blood tests are often the first clue.
When a Primary Care Doctor Is Enough
Your primary care doctor can handle many cases of high creatinine. This is often true when:
- The increase is mild and has a clear temporary cause
- Repeat tests return to normal
- Kidney function is mildly reduced but stable over time
- Blood pressure and blood sugar are well controlled
In these situations, your doctor may repeat blood work, check your urine for protein, review your medications, and help you manage conditions that strain the kidneys.
When You May Need a Nephrologist
A nephrologist is a doctor who specializes in kidney health. A referral often makes sense when:
- Your eGFR drops below 30
- Your kidney function declines quickly
- Your urine shows large amounts of protein
- You have blood in your urine without a clear cause
- Your blood pressure stays high despite several medications
- You have frequent kidney stones or a family history of kidney disease
- Potassium or other mineral levels in your blood are off balance
Your primary care doctor may also refer you if the cause of high creatinine is unclear.
What to Expect From a Nephrology Referral
Your first visit usually focuses on finding the cause and measuring how well your kidneys work. The nephrologist will review your health history, medications, and past lab results. Expect some or all of the following:
- Repeat blood and urine tests to confirm results and look for protein
- A kidney ultrasound to check size, structure, and possible blockages
- A medication review to spot drugs that may stress the kidneys, such as certain over-the-counter pain relievers
- A kidney biopsy in some cases, when other tests don’t explain the problem
From there, the specialist builds a plan. It may include blood pressure control, medications that protect the kidneys, and diet changes. Your nephrologist and primary care doctor typically share information and coordinate your care.
What to Remember
Creatinine is a muscle waste product, and high levels can signal that your kidneys aren’t filtering well. Temporary factors like dehydration or exercise can raise it, so repeat testing matters. Primary care doctors can manage mild, stable changes. A nephrologist becomes important when kidney function drops sharply, protein or blood appears in the urine, or the cause is unclear. With early attention and the right team, many people protect their kidney function for years.