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Blood Test Tracker

Urine Granular Casts

A count of granular casts, tiny tube-shaped particles in urine that can form when kidney cells or protein break down.

AI-verified against cited sources. Awaiting expert reviewLOINC 5793-5

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What it is

Casts are tiny tube-shaped particles that form in the kidney's small tubes and wash out in urine. Granular casts look grainy under a microscope. The grains come from broken-down cells and protein. Labs count casts per low-power field (LPF) as part of a complete urinalysis. Some labs list fine and coarse granular casts on separate lines.

Why it matters

Granular casts are seen less often than hyaline casts. Very hard exercise has been linked to a few of them. They can also show up with several kidney conditions, so clinicians read them together with your urine protein and blood, your kidney blood tests and your symptoms. Quest and Labcorp both list none seen as the expected result.

If it’s high

Granular casts mean the sample contained grainy casts. A few can be seen after very hard exercise. They are also linked to several kidney conditions, so a repeat urine test and your other kidney results help put them in context. Your clinician looks at the whole picture before drawing any conclusion.

Common causes

  • Very hard or long exercise (in one study, a runner with many hyaline casts also had granular casts after a 100 km race)
  • Short-term kidney injury, such as acute tubular necrosis, where dense brownish ("muddy brown") granular casts are a classic finding
  • Many other kinds of kidney disease

What can help

  • Tell your clinician about recent hard exercise, illness and all medicines you take
  • Ask whether to repeat the urine test after rest and fluids
  • Ask whether your kidney blood tests (creatinine and eGFR) and urine protein should be checked or compared with past results

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: up to 0 /LPF. Source: Quest Diagnostics, Labcorp.

What can affect your result

  • Very hard or long exercise
  • Hydration and how concentrated the urine is
  • Time between collection and testing, and how acidic, alkaline or dilute the urine is
  • The method used (manual microscopy per LPF, or an automated analyzer)
  • The person reading the slide, and whether fine and coarse granular casts are counted together
  • Urine that sits too long, or is alkaline or very dilute, can break casts down, so counts read low. A review notes that European guidance asks labs to examine urine within about 1 hour at room temperature or 4 hours if refrigerated.
  • Very hard or long exercise has been linked to granular casts in a small study of ultra-marathon finishers, with urine collected right after the race.
  • Counts depend on how the sample is spun and on who reads the slide. Manual microscopy has limited agreement between readers, and automated analyzers count per microliter, which does not convert directly to per LPF.

A fresh midstream (clean-catch) sample is preferred. A second-morning sample is often better than the first void of the day, because casts can break down while urine sits in the bladder overnight. Reflects the sample you gave. It can change from day to day with illness, hydration and exercise.

When to talk to a clinician

Ask the clinician who ordered the test what the result means and whether a repeat is needed. Contact them sooner if you also have swelling, much less urine than usual, foamy or dark urine, or blood in your urine. If you have chest pain, trouble breathing or confusion, call 911 or your local emergency number.

Questions you could ask

  • Which parts of my urine report should I watch over time?
  • Could recent hard exercise or illness explain this?
  • Should we repeat the urine test, and when?
  • How do these casts fit with my urine protein and my kidney blood tests?

Questions people ask

Are granular casts always a sign of kidney disease?

No. Very hard exercise has been linked to them. They are also linked to several kidney conditions, so a clinician reads them with your other urine and kidney results, and a repeat test is common.

My report lists fine and coarse granular casts separately. Does it matter?

Some labs print them on separate lines and others combine them. The type alone does not give a diagnosis. Your clinician looks at the whole urine report.

Why does my lab say "none seen" is expected?

Quest and Labcorp list none seen as the expected result for casts, so any cast gets flagged. That doesn't tell you the cause. Ask your clinician what it means for you.

Show the science and sources

For clinicians and researchers

Granular casts form from degenerated cellular material and aggregated protein inside the tubules; they are described as fine or coarse. A review calls dense brownish ('muddy brown') granular casts, especially with renal tubular epithelial cell casts, a distinguishing finding in acute tubular necrosis, and describes urine sediment scoring systems that count granular casts and renal tubular epithelial cells to help predict acute tubular necrosis and a more severe course. MedlinePlus notes that granular casts are a sign of many types of kidney disease. After a 100 km ultra-marathon, one finisher with more than 25 hyaline casts per LPF also had granular casts. Quest result code 30010500 'GRANULAR CAST' maps to LOINC 5793-5, and Quest's expected result is 'None seen'. Labcorp's sample report prints Casts per LPF (reference 'None seen') and a separate Cast Type line. LOINC also has separate fine (32680-1) and coarse (33393-0) low-power-field codes. Automated sediment analyzers report casts per microliter (for example LOINC 53282-0 for computer-assisted counts), which cannot be converted to per-LPF without the lab's field and prep, so only per-LPF is modeled here.

LOINC 5793-5 (primary), 88974-1, 25160-3, 32680-1, 33393-0, 105086-3. Specimen: urine.

Sources

  1. Urinalysis, Complete (test code 5463), Quest Diagnostics
  2. Urinalysis, Complete (test 003772), sample patient report, Labcorp (2026)
  3. Urinary casts (MedlinePlus Medical Encyclopedia), MedlinePlus, U.S. National Library of Medicine
  4. Diagnostic Utility of Urine Microscopy in Kidney Diseases, Indian Journal of Nephrology (2024)
  5. Athletic pseudonephritis in male cross-country ultra-marathoners: a comparative observational study, Frontiers in Physiology (2025)
  6. Navigating complex cardiac complications: A case report of alcoholic cardiomyopathy and right atrial thrombosis, Medicine (Baltimore) (2024)

AI-verified against cited sources. Awaiting expert review. Last reviewed 2026-10-03. How we build and check these pages.

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