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Introduction ⬇

Hyaline casts are clear, colorless casts that are formed when a renal protein within the tubules (Tamm–Horsfall protein) precipitates and gels. Tamm–Horsfall protein is excreted at a fairly constant rate by the tubule cells and provides immunologic protection from infection. Hyaline casts are the most commonly occurring casts in urine and can be seen in physiologic states such as strenuous exercise and even in the mildest kidney disease. They are not associated with any one particular disorder.

Normal Findings ⬆ ⬇

Occasional, 0–2/lpf (10× objective)

Procedure ⬆ ⬇

  1. Observe the Procedure for Microscopic Urine Examination on pages xxx through xxx of this chapter.

  2. Examine urinary sediment microscopically for casts under low power.

  3. Examine casts when the light intensity is reduced because they are colorless and transparent.

  4. Note that wrinkling and convoluting of the cast occurs as it ages.

Clinical Implications ⬆ ⬇

  1. Hyaline casts indicate possible damage to the glomerular capillary membrane. These casts appear in:

    1. Glomerulonephritis, pyelonephritis

    2. Malignant hypertension

    3. Chronic kidney disease

    4. Heart failure

    5. Diabetic nephropathy

  2. Hyaline casts may be a temporary phenomenon in the presence of:

    1. Fever (dehydration)

    2. Postural orthostatic lordotic strain

    3. Emotional stress

    4. Strenuous exercise

    5. Heat exposure

  3. Nephrotic syndrome may be suspected when large numbers of hyaline casts appear in the urine together with significant proteinuria, fine granular casts, fatty casts, oval bodies, or fat droplets.

  4. In cylindroiduria, large numbers of hyaline casts may be present, but protein in the urine is absent. Cylindroids are hyaline casts that have been formed at the junction of the ascending loop of Henle and therefore have tapered ends.

Clinical Alert

Casts may not be found even when proteinuria is significant if the urine is dilute (1.010 SG) or alkaline. In these cases, the casts are dissolved as soon as they are formed

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain purpose of test, procedure for random urine sample collection, and interfering factors.

  2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Monitor appropriately. Counsel the patient regarding abnormal findings.

  2. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆

Delays between specimen collection and testing may result in disintegration of casts.