Skip to content
Blood Test Tracker

Urine Creatinine, Random

How much creatinine, a muscle waste product, is in one urine sample. It shows how concentrated the urine is and is used to correct other urine results.

AI-drafted. Awaiting verificationAlso called UCr, U CreatLOINC 2161-8

Check your result

Sex (optional)

Type your result to see where it falls.

Nothing you type here leaves your browser.

What it is

Creatinine is a waste product made by your muscles and removed by your kidneys into urine. It leaves at a fairly steady daily rate, so how much is in one sample mainly shows how watery or concentrated that sample is. Labs measure it mostly to put other urine results in context, such as albumin or protein in a ratio. It is not a kidney test on its own.

Why it matters

Urine gets more or less watery depending on how much you drink and sweat. Dividing another urine result by the creatinine in the same sample corrects for that, which is how the urine albumin-to-creatinine ratio works. A very low creatinine can also show that a sample was too dilute to test reliably, for example on a drug-test report. A single creatinine value says little about kidney health. Blood creatinine and eGFR are used for that.

If it’s low

A lower value usually means your urine was dilute, for example after drinking a lot of fluid or taking a water pill. Dilute urine can make other urine results read lower than they really are. On a drug-test report, a very low creatinine can lead to the sample being called dilute.

Common causes

  • Drinking a lot of fluid before the test
  • Water pills (diuretics)
  • Low muscle mass

What can help

  • Ask whether the test should be repeated with a less dilute sample, such as first-morning urine
  • Ask your lab or clinician how much fluid to drink before a repeat sample

If it’s high

A higher value usually means your urine was concentrated, for example after drinking little, sweating a lot, or first thing in the morning. It can also be higher with more muscle mass or after a meal with a lot of cooked meat. On its own it is not a sign of kidney disease.

Common causes

  • Concentrated urine from drinking little, sweating or hot weather
  • A more concentrated sample, such as first-morning urine
  • Higher muscle mass
  • Cooked meat eaten shortly before the test

What can help

  • Ask your clinician whether your sample was more concentrated than usual and whether that changes how your other urine results are read

Usual ranges

What labs print as the reference range, by who was tested. Ranges differ a little between labs, so the range on your own report is the one your result is judged against.

For adults: 16–326 mg/dL. Source: Mayo Clinic Laboratories.

What can affect your result

  • How much you have had to drink, sweat or urinate recently
  • Time of day: first-morning urine is usually more concentrated
  • Muscle mass, age and sex
  • Cooked meat and creatine supplements
  • Drinking a lot of fluid, or taking a water pill (diuretic), dilutes the urine and lowers the value.
  • Little fluid intake, sweating or hot weather concentrates the urine and raises the value.
  • Cooked meat can temporarily raise creatinine.
  • Muscle mass, age and sex change how much creatinine your body makes.

Any time. Urine gets more or less concentrated through the day and with how much you drink, so a single value is mostly used to correct another urine result, not read alone. Reflects only the sample you gave, so it can differ a lot from one sample to the next.

Questions you could ask

  • Which of my results use this creatinine value in a ratio?
  • Was my sample more concentrated than usual, and does that change how my other urine results are read?
  • Was my urine too dilute for this test, and should I give a new sample?
  • How much should I drink before a repeat sample?

Questions people ask

Why was my urine creatinine measured if my kidneys are fine?

It is usually a helper test. Labs use it to correct other urine results for how watery the sample is, such as albumin or protein, or to check a sample's strength. It is not meant to judge your kidneys by itself.

My report says the urine was dilute. What does that mean?

It means the sample was more watery than usual, most often from drinking a lot before the test. Dilute urine can make other results read low, so your clinician or program may ask for a new sample. In federal workplace drug testing, dilute is reported when creatinine is 2 to under 20 mg/dL and specific gravity is in a narrow low range.

How do I convert mg/dL to mmol/L?

Multiply mg/dL by 0.0884, so 100 mg/dL is about 8.8 mmol/L. To go the other way, multiply mmol/L by 11.31.

Show the science and sources

Units

  • 1 mg/dL = 1 mg/dL
  • 1 mg/dL = 0.0884 mmol/L
  • 1 mg/dL = 88.4 µmol/L
  • 1 mg/dL = 0.01 g/L
  • 1 mg/dL = 10 mg/L

Open the Urine Creatinine unit converter

Is a change real?

Urine Creatinine naturally varies about 36.3% from test to test in the same healthy person. Between two results from the same lab, a rise of 199% or more, or a fall of 67% or more, is unlikely to be day-to-day noise or lab variation (95% reference change value). Source: Desirable Biological Variation Database specifications, 2014 update (Minchinela J, Ricos C, et al.; the 'Ricos database', a compilation of median published CVI/CVG).

For clinicians and researchers

Creatinine is made from muscle creatine at a fairly constant rate and is filtered and partly secreted by the kidney, so its concentration in a spot sample is mainly a function of urine volume. Mayo Clinic Laboratories lists a colorimetric method and an adult interval of 16-326 mg/dL; ARUP publishes no interval for random urine. The main uses are as the denominator of urine analyte-to-creatinine ratios (albumin, protein, calcium, metals), which correct for dilution, and for specimen validity checks. In US federal workplace drug testing (HHS Mandatory Guidelines for urine, 2023), a primary specimen is reported dilute when creatinine is at least 2 and below 20 mg/dL with specific gravity above 1.0010 and below 1.0030, and substituted when creatinine is below 2 mg/dL with specific gravity at or below 1.0010 or at or above 1.0200.

LOINC 2161-8 (primary), 35674-1, 14683-7. Specimen: urine.

Sources

  1. CRETR: Creatinine, Random, Urine (Mayo Clinic Laboratories catalog, mirrored at testcatalog.org), Mayo Clinic Laboratories
  2. Creatinine, Urine - per 24h (test 0020473), which notes random urine has no reference intervals, ARUP Laboratories
  3. Creatinine Test, MedlinePlus (U.S. National Library of Medicine)
  4. Mandatory Guidelines for Federal Workplace Drug Testing Programs (urine), 88 FR 70768, U.S. Department of Health and Human Services (Federal Register) (2023)
  5. Creatinine (PubChem CID 588), National Center for Biotechnology Information
  6. LOINC codes verified with the NLM Clinical Tables LOINC search, U.S. National Library of Medicine

AI-drafted. Awaiting verification. Last reviewed 2026-10-03. How we build and check these pages.

Calculators

Related markers