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Casts

Urine Analysis Biomarker

Sample Needed

Collection Type: Urine

Body System

Related System: Urine Analysis

Overview

Casts are microscopic, tube-shaped particles formed in the renal tubules and collecting ducts from precipitation of Tamm-Horsfall protein mixed with cellular elements. Urine microscopy for casts evaluates number and type (hyaline, RBC, WBC, granular, waxy, fatty, epithelial) to help localize kidney disease. Different casts point to different processes: RBC casts suggest glomerular inflammation, WBC casts suggest renal parenchymal infection or interstitial nephritis, and granular/waxy casts signal tubular injury or chronic damage. Testing is indicated for hematuria, dysuria, fever, edema, unexplained hypertension or abnormal renal function. Occasional hyaline casts can be normal after exercise or dehydration; elderly patients may have low-level casts more often.

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: Urine analysis / routine urinalysis - Symptoms: blood in urine, painful urination, fever, edema, reduced urine output, unexplained azotemia - Diagnoses/monitoring: glomerulonephritis, pyelonephritis, acute tubular necrosis, nephrotic syndrome, chronic kidney disease - Abnormal reasons: infection, inflammation, ischemia, toxins, heavy exercise, dehydration - Biological meaning: presence/type of cast indicates site and severity of renal injury - Lifestyle/family: recent vigorous exercise, low fluid intake, family history of hereditary kidney disease

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Understanding Test Results

0–2 casts/LPF: generally normal; occasional hyaline casts may follow exercise, dehydration, or concentrated urine.
3–10 casts/LPF: mild increase—may reflect early or mild tubular irritation, low-grade infection, or transient renal stress; consider repeat testing and correlation with symptoms and urine sediment.
>10 casts/LPF or many casts: significant renal involvement—evaluate cast type: RBC casts are strongly suggestive of glomerulonephritis; WBC casts point toward pyelonephritis or interstitial nephritis; muddy brown granular casts indicate acute tubular necrosis; waxy casts suggest chronic renal failure; fatty casts indicate heavy proteinuria/nephrotic syndrome.
False positives/negatives can occur with improper collection, concentrated urine, or delayed processing; abnormal findings warrant urine culture, renal function tests, and nephrology follow-up.

Normal Range

0–2 casts/LPF

FAQs

Q: What do casts mean?

A: Urine casts are microscopic, tube-shaped particles formed in kidney tubules from protein and trapped cells. Their type helps identify disease: hyaline casts can occur with dehydration or after exercise; red-cell casts suggest glomerular inflammation; white-cell casts indicate kidney infection or interstitial nephritis; granular or waxy casts point to chronic or severe renal injury; fatty casts are seen with nephrotic syndrome and need further evaluation.

Q: What are casts of characters?

A: Renal casts are cylindrical microscopic particles formed when protein and cells precipitate within kidney tubules. Their composition—hyaline, red blood cell, white blood cell, granular, waxy or fatty—helps identify site and type of kidney injury. RBC casts suggest glomerulonephritis; WBC casts indicate tubulo‑interstitial infection or inflammation; granular and waxy casts point to tubular injury or chronic kidney disease; fatty casts occur in nephrotic syndrome.

Q: Is it casts or castes?

A: Use \

Q: What is cast in medical terms?

A: A cast is a rigid external shell applied around a limb or body part to immobilize and protect broken bones, severe sprains, or post‑operative sites. Made from plaster or fiberglass, it maintains proper bone alignment while tissues heal, reduces pain, and limits movement. Cast application follows fracture reduction and requires regular monitoring for swelling, tightness, skin problems, or circulation and nerve changes.

Q: How are casts removed?

A: Casts are usually removed in clinic with an oscillating cast saw that cuts the rigid material without harming skin; the technician then uses a spreader to open the cast and scissors to remove padding and stockinette. The limb is inspected, cleaned, and any dead skin washed off; nails are checked and exercises or splinting may be advised. Removal may feel vibration, noise, and warmth but is painless.

Q: What is the normal range of casts in urine?

A: Normal urine may show no casts or only occasional hyaline casts—typically up to 0–2 casts per low-power field (LPF). Presence of RBC, WBC, granular, waxy, or fatty casts is generally abnormal and suggests renal pathology. Interpretation depends on clinical context, hydration, and recent exercise; further evaluation is advised if atypical casts appear or numbers increase.