Lab Values & ABGs Practice Test #2: CBC and Coagulation

Answer: C. Have the client use an electric razor and a soft-bristled toothbrush.

Rationale: A typical adult platelet range is about 150,000 to 400,000/mm³ (ranges vary by lab). A count this low puts the client at high risk for bleeding, so the nurse uses bleeding precautions: an electric razor, a soft-bristled toothbrush or toothettes, no rectal temperatures, suppositories or enemas, and no aspirin or NSAIDs unless prescribed. Rectal thermometers and firm flossing can injure tissue and cause bleeding. Intramuscular injections are avoided when possible, and any injection site gets firm pressure, never massage. The nurse also checks for petechiae, bruising, bleeding gums, blood in urine or stool, and changes in level of consciousness. Whether a platelet transfusion is needed is decided by the provider and facility guidelines.

Answer: A. 360/mm³; the client is at high risk for infection and needs neutropenic precautions per facility policy.

Rationale: ANC = total WBC × (percent segmented neutrophils + percent bands). Here that is 1,800 × (0.18 + 0.02) = 1,800 × 0.20 = 360/mm³. An ANC under 1,500/mm³ is generally called neutropenia, and under 500/mm³ is severe neutropenia with a high risk of serious infection (cut-offs can vary slightly by source and facility). The nurse follows the facility's neutropenic precautions, monitors closely for fever and other signs of infection, and reports a fever right away, because the usual signs such as pus and redness may be absent. 1,800 is the total WBC, not the ANC. Leaving out the bands gives 324, which underestimates the count; bands are immature neutrophils and are included.

Answer: D. Hemoglobin 9.6 g/dL, MCV 71 fL, ferritin low

Rationale: Chronic blood loss, such as heavy menstrual bleeding, slowly drains iron stores. Iron-deficiency anemia is typically microcytic: a low hemoglobin, a low MCV (mean corpuscular volume, typical adult range about 80 to 100 fL), and a low ferritin, which reflects low iron stores. A high MCV with a low hemoglobin (macrocytic) points toward vitamin B12 or folate deficiency. A normal hemoglobin and MCV is a normal result for an adult woman (typical range about 12 to 16 g/dL; ranges vary by lab). A normal-sized red cell with a high reticulocyte count suggests the marrow is responding to acute blood loss or hemolysis rather than an iron shortage.

Answer: B. The results suggest hemoconcentration from a fluid volume deficit.

Rationale: Hematocrit is the percentage of blood volume made up of red blood cells. When the client loses fluid, the plasma volume shrinks while the number of red cells stays the same, so the hematocrit and hemoglobin rise. A typical adult female hematocrit range is about 37% to 47% (ranges vary by lab). A rise from 42% to 54% over days of vomiting and diarrhea, together with a high BUN, points to dehydration, not a new blood disorder. Polycythemia vera is a chronic marrow disease and would not appear suddenly with fluid losses. An acute bleed lowers the hematocrit once fluid shifts in, and fluid overload dilutes the blood and lowers it. The nurse assesses for other signs of fluid deficit (orthostatic vital signs, dry mucous membranes, low urine output) and reports the findings.

Answer: D. The results show a shift to the left, which suggests an acute bacterial infection that should be reported.

Rationale: A typical adult WBC range is about 5,000 to 10,000/mm³, and bands usually make up only a small percentage, often about 0 to 5% (ranges vary by lab). When the body fights an acute bacterial infection, the bone marrow releases neutrophils faster, including immature band forms. A rising band percentage is called a shift to the left. With a fever on postoperative day 3 after bowel surgery, the nurse is concerned about a wound infection, anastomotic leak, pneumonia, or urinary tract infection, and reports the findings promptly. A mild WBC rise can be seen in the first day or so after surgery, but not with this degree of bands and a new fever days later. Viral infections more often raise lymphocytes, and allergic reactions raise eosinophils.

Answer: A. Hold the warfarin dose and notify the health care provider promptly.

Rationale: The INR measures how long blood takes to clot compared with normal. For many clients taking warfarin for atrial fibrillation, the provider's target is about 2 to 3, but the target is set for each client and can be higher for some conditions, such as certain mechanical heart valves. An INR of 6.1 with pink urine (possible hematuria) means a high risk of bleeding. The nurse holds the dose, notifies the provider promptly, assesses for other bleeding (stool, gums, bruising, neurologic changes), and anticipates orders such as vitamin K. Serious bleeding may need other reversal agents chosen by the provider. Protamine reverses heparin, not warfarin. Giving the next dose would worsen the risk. Suddenly changing vitamin K intake makes warfarin control unpredictable; clients are taught to keep vitamin K intake consistent, not to use food to treat a high INR.

Answer: C. Platelet count

Rationale: Low-molecular-weight heparins such as enoxaparin have a predictable effect and do not need routine aPTT monitoring. The nurse monitors the platelet count because any heparin product can cause heparin-induced thrombocytopenia (less often with low-molecular-weight heparin than with unfractionated heparin), and also watches hemoglobin and hematocrit for bleeding. Kidney function matters because enoxaparin is cleared by the kidneys, and some clients (for example, those with kidney impairment, obesity, or pregnancy) may have anti-factor Xa levels checked as the provider orders. PT/INR monitors warfarin. aPTT is commonly used to monitor an unfractionated heparin infusion. The reticulocyte count reflects red cell production and is not used to monitor anticoagulants.

Answer: B. Stop all heparin, including heparin flushes, and notify the provider immediately.

Rationale: A platelet drop of more than 50% from baseline, typically 5 to 10 days after heparin is started, together with a new clot, strongly suggests heparin-induced thrombocytopenia (HIT). HIT is an immune reaction that causes clotting, not bleeding, so a new swollen, painful arm suggests a new thrombosis. All heparin must be stopped, including heparin flushes and heparin-coated catheters, and the provider notified right away. The provider will usually order HIT antibody testing and a non-heparin anticoagulant such as argatroban, according to facility protocol. Enoxaparin is a heparin and is avoided in HIT. Platelet transfusions are generally avoided unless there is serious bleeding, because they can add to clot formation. Warm compresses do nothing to treat the cause.

Answer: A. Platelets 42,000/mm³, fibrinogen 90 mg/dL, D-dimer elevated, PT prolonged

Rationale: In DIC, an illness such as sepsis triggers widespread clotting. Platelets and clotting factors are used up faster than they can be made, so the platelet count and fibrinogen fall (typical fibrinogen range is about 200 to 400 mg/dL; ranges vary by lab) and the PT and aPTT become prolonged. At the same time, clots are being broken down, so fibrin breakdown products such as D-dimer rise. The result is bleeding and clotting together. The second set is normal. Low platelets with normal clotting tests and fibrinogen suggest an isolated platelet problem, such as immune thrombocytopenia. A prolonged PT alone suggests warfarin use, vitamin K deficiency, or liver disease. Treatment focuses on the cause, with blood products as the provider orders, and the nurse monitors closely for bleeding and signs of clots.

Answer: D. Platelets 28,000/mm³ in a client scheduled for a lumbar puncture this morning

Rationale: A platelet count of 28,000/mm³ is far below the typical range of about 150,000 to 400,000/mm³ (ranges vary by lab). A lumbar puncture with this count risks bleeding around the spinal cord, which can cause a spinal hematoma and permanent nerve damage. The provider needs this result before the procedure so it can be delayed or the platelets corrected; the safe threshold depends on the procedure and facility guidelines. The INR is within the provider's documented target for this client. A stable hemoglobin of 11.0 g/dL is common in chronic kidney disease, which reduces erythropoietin. A small platelet drop that stays within the normal range on enoxaparin does not meet the pattern for heparin-induced thrombocytopenia, though the nurse continues to monitor it.