CPT® Code 85555

Official Description

Osmotic fragility, RBC; unincubated

Common Language Description

The CPT® Code 85555 refers to a laboratory test that assesses the osmotic fragility of red blood cells (RBCs) in an unincubated state. Osmotic fragility is a critical measure of how susceptible red blood cells are to hemolysis, which is the process of rupture or destruction of these cells when they are subjected to osmotic stress. In this test, red blood cells are exposed to hypotonic saline solutions, which causes water to enter the cells. As the cells swell from the influx of fluid, they eventually reach a point where they can no longer withstand the pressure and rupture. This test is particularly useful in diagnosing conditions such as hereditary spherocytic hemolytic anemia, where the red blood cells are abnormally shaped (spherocytes) and have a reduced capacity to expand. Consequently, these spherocytic cells are more likely to hemolyze under less extreme hypotonic conditions compared to normal red blood cells. The results of the unincubated osmotic fragility test can indicate positive results when hemolysis is observed in three or more specific concentrations of sodium chloride (NaCl). Additionally, the test can reveal increased fragility in various hemolytic disorders, recent blood transfusions, and specific anemias, while decreased fragility may be noted in conditions such as post-splenectomy and chronic liver disease. The test is performed on a blood sample obtained through venipuncture, and the analysis is conducted using techniques such as spectrophotometry or osmotic lysis-flow cytometry.

1. Indications

The osmotic fragility test (CPT® Code 85555) is indicated for the evaluation of patients with suspected hereditary spherocytic hemolytic anemia. This condition is characterized by the presence of spherocytic red blood cells, which are more prone to hemolysis under hypotonic conditions. Additionally, the test may be utilized in the assessment of other conditions associated with increased fragility of red blood cells, including:

Immunohemolytic Anemia - A condition where the immune system mistakenly attacks and destroys red blood cells.
Recent Blood Transfusion - The test may help evaluate the compatibility and integrity of transfused red blood cells.
Congenital Nonspherocytic Hemolytic Anemia - Conditions caused by enzyme deficiencies such as glucose-6-phosphate dehydrogenase (G-6-PD) or pyruvate kinase deficiency.

Furthermore, the test can also be relevant in cases where decreased fragility is suspected, such as in patients who have undergone splenectomy, or those with chronic liver disease, iron deficiency anemia, thalassemia, hyponatremia, polycythemia vera, and sickle cell disease.

2. Procedure

The procedure for conducting the osmotic fragility test involves several key steps, which are outlined as follows:

Step 1: Sample Collection A blood sample is obtained from the patient through a venipuncture. This step is crucial as it provides the whole blood necessary for the test.
Step 2: Preparation of Hypotonic Solutions Various concentrations of sodium chloride (NaCl) solutions are prepared, typically including concentrations of 0.50 g/dl, 0.60 g/dl, 0.65 g/dl, and 0.75 g/dl. These solutions will be used to assess the osmotic fragility of the red blood cells.
Step 3: Incubation (if applicable) In the case of an unincubated test, the blood sample is directly tested. However, if an incubated test is performed, the sample may be heated prior to testing to magnify any abnormal results.
Step 4: Testing The whole blood is then subjected to the prepared hypotonic saline solutions. The red blood cells are observed for hemolysis, which indicates their fragility. The degree of hemolysis is assessed at each concentration of NaCl.
Step 5: Analysis The results are analyzed, and a positive result for osmotic fragility is determined when hemolysis is noted in three or more of the NaCl concentrations tested.

3. Post-Procedure

After the osmotic fragility test is completed, the patient may be monitored for any immediate reactions, although the test is generally well-tolerated. The results will be interpreted by a qualified healthcare professional, who will consider them in conjunction with the patient's clinical history and other laboratory findings. It is important to communicate the results to the patient and discuss any further diagnostic steps or treatments that may be necessary based on the findings. Additionally, proper documentation of the test results and any relevant clinical information is essential for ongoing patient care and management.

Short Descr	RBC OSMOTIC FRAGILITY
Medium Descr	OSMOTIC FRAGILITY RBC UNINCUBATED
Long Descr	Osmotic fragility, RBC; unincubated
Status Code	Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days	XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC)	9 - Not Applicable
Multiple Procedures (51)	9 - Concept does not apply.
Bilateral Surgery (50)	9 - Concept does not apply.
Physician Supervisions	09 - Concept does not apply.
Assistant Surgeon (80, 82)	9 - Concept does not apply.
Co-Surgeons (62)	9 - Concept does not apply.
Team Surgery (66)	9 - Concept does not apply.
Diagnostic Imaging Family	99 - Concept Does Not Apply
CLIA Waived (QW)	No
APC Status Indicator	Conditionally packaged laboratory tests
Type of Service (TOS)	5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS)	T1H - Lab tests - other (non-Medicare fee schedule)
MUE	1
CCS Clinical Classification	233 - Laboratory - Chemistry and Hematology

90	Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.