Updated on: November 29, -0001

Misconceptions Related to Lab Results

By Terri Millerd, BSN, RN, CCDS, MLT(ASCP)
Original story posted on: August 31, 2016

When someone finds out that I have a laboratory degree, along with nursing and Certified Clinical Documentation Specialist (CCDS) certification, they usually have a few questions for me. So in this article, I am going to discuss some of the most frequently asked questions, most misunderstood ideas, and some tips that will make looking at lab work simpler.

There are two questions that I hear on a regular basis. They are “how do you know if a lab result is abnormal?” and “what does the manual differential mean in a complete blood count (CBC)?”

How you can tell if a lab result is abnormal is to look at the facility reference range. These will differ from facility to facility. For example, Cleveland Clinic notes that hyponatremia is any sodium level lower than 136, and hypernatremia is a sodium level greater than 145. Medscape recognizes hyponatremia as a sodium level of less than 135, with severe hyponatremia if the level is less than 125, and hypernatremia as a sodium level greater than 145.

Most physicians I have spoken with think hyponatremia is only valid if the level is less than 131, since healthy patients can have sodium levels in the range of 131 to 135. So first I would look at the facility’s reference range, then look at the treatment the patient is receiving and make your determination whether to query or not.

As for the second question, the following are different types of white blood cells that may be included in a manual differential: blasts, promyeloblasts, myelocytes, bands, segmented neutrophil, lymphocytes, monocytes, eosinophils, and basophils. The normal ranges for cells in the differential are: neutrophils: 40 to 60 percent; lymphocytes: 20 to 40 percent; monocytes: 2 to 8 percent; eosinophils: 1 to 4 percent; basophils: 0.5 to 1 percent; and bands (young neutrophils): 0 to 3 percent. Blasts, promyeloblasts and myelocytes are very immature forms.

There are no normal ranges for these because they are not normally seen on a WBC differential. These will usually be seen in cancers and myelodysplastic syndromes (MDS). Bands and increased numbers of segmented neutrophils are usually seen along with sepsis, acute bacterial infections, and acute stress or trauma. An increased lymphocyte count is usually indicative of an acute viral infection, leukemia, multiple myeloma, infectious mononucleosis, or hepatitis. A low lymphocyte count can be indicative of certain viral infections, for example influenza and hepatitis, fasting, severe physical stress, use of corticosteroids, chemotherapy, or radiation, lupus, rheumatoid arthritis, chronic infections such as AIDS, or tuberculosis and certain cancers such as leukemias or lymphomas.

Increased number of monocytes occurs along with chronic infections, autoimmune disorders, and in certain cancers. An increased eosinophil percentage usually indicates an allergic response, but can also indicate parasitic infection, cancer, connective tissue disorder, medications, and endocrinpathies. Basophils will be increased with a severe food allergy, chronic myelogenous leukemia, Collagen vascular disease, myeloproliferative disease, or a varicella infection. Basophils will be decreased in an acute infection, cancer, and/or severe injury. As you can see, each type of white blood cell can signify a disease process in a patient.

So now that we have discussed the most frequently heard questions, I wanted to talk about misconceptions about lab results and tips. 

Some misunderstood ideas nurses have about lab results are these: hematocrit is an actual test, all urinary casts are the same, and C-reactive protein tests are just to determine the presence or absence of sepsis.

Hematocrit is actually a calculation, using the hemoglobin as a base. To figure out the hematocrit level, you need to multiply the HGB by three. For example, if the hemoglobin level was 12, then the hematocrit would be 36.

All urinary casts are not the same. Casts are formed when flow inside the kidney tubules stops and material (WBCs, RBCs, fat, epithelial cells, etc.) solidifies. There are five different times of casts: hyaline, granular, waxy, tubular, and WBC. A hyaline cast is the most frequently seen. A few may be found in a normal patient’s urine specimen or in a patient who has prerenal azotemia. Granular casts appear along with ATN, nephrotic syndrome, and renal disease. Waxy casts are found in patients with CKD, diabetic nephropathy, malignant HTN, and glomerulonephritis. Tubular epithelial casts are noted in patients with glomerulonephritis. WBC casts can signify that the patient has acute pyelonephritis.

C-reactive protein (CRP) tests can be ordered for different reasons. It may be ordered to determine if the patient has sepsis or to monitor chronic inflammatory conditions such as inflammatory bowel disease, lupus, vasculitis, or arthritis, for example. A high-sensitivity C-reactive protein (hs-CRP) test is being used to evaluate patients for increased risk of coronary artery disease. A hs-CRP test is most useful when the patient is at a moderate risk of myocardial infarction, so not everyone should have this test ordered.

Here are some tips for looking at lab results when performing a clinical documentation improvement (CDI) review. First, look at your lab results first, before looking at the provider documentation, because it can give you clues as to what should be documented. For example, if you notice that the patient had a hemoglobin level of 8.0 and an iron level of 17, then you would know to look for iron deficiency anemia and/or acute blood loss anemia in the provider documentation. Sometimes what lab tests are ordered can tell you what the provider was trying to rule out (or verify the presence of). For example, ordering an amylase and lipase on a patient with abdominal pain can indicate that the provider was checking to see if the patient had pancreatitis. Always check the facility reference ranges and any flags, notes, or comments. For example, on a chemistry panel, say there is a comment on elevated potassium levels that reads “hemolyzed specimen.” This indicates that maybe the potassium is falsely elevated. As a floor nurse, you would not want to give Kayexalate to a patient who had a falsely elevated potassium level of 5.8. It should be repeated and then treated. As a CDI specialist, you would want to wait to see the repeated potassium before querying for hyperkalemia.

In conclusion, remember, always look at your facility’s reference range and lab result comments before querying. If you are unsure why a specific test was ordered or what the results indicate, look it up using a reputable source or website, or call the laboratory department at your facility and ask to speak to a tech. They should be glad to answer your questions. I hope this article has given you a different perspective on lab results, and some good information that will make your CDI/coding job easier.

About the Author

Terri Millerd has more than 20 years of experience in clinical nursing, laboratory work, and clinical documentation improvement. She is a registered nurse, certified clinical documentation specialist (CCDS) from the Association of Clinical Documentation Improvement Specialists (ACDIS), and a board-certified medical laboratory technician as denoted by the ASCP (American Society of Clinical Pathologists).

Contact the Author 

tmillerd@panaceainc.com 

Comment on this Article

editor@racmonitor.com

References

(1)   http://www.clevelandclinicmeded.com/medicalpubs/diseasemanagement/nephrology/hyponatremia-and-hypernatremia/

(2)   http://emedicine.medscape.com/article/242166-overview

(3)   http://emedicine.medscape.com/article/241094-overview

(4)   http://www.merckmanuals.com/home/blood-disorders/white-blood-cell-disorders/monocyte-disorders

(5)   http://www.merckmanuals.com/home/blood-disorders/white-blood-cell-disorders/lymphocytopenia

(6)   http://emedicine.medscape.com/article/199879-overview

(7)   https://medlineplus.gov/ency/article/003657.htm

(8)   Panacea CDI manual, 2016.

(9)   Ringsrud, Mt(Ascp) Karen M. "Casts in the Urine Sediment." Laboratory Medicine 32.4 (2001): 191-93. Web.

(10) https://labtestsonline.org/understanding/analytes/crp/tab/test/

(11) http://www.mayoclinic.org/tests-procedures/c-reactive-protein/basics/definition/prc-20014480