Lab Values & ABGs Practice Test #3: Renal, Liver and Glucose

Answer: B. The high BUN is most likely from digested blood in the gut and fluid volume loss, and the stable creatinine suggests kidney function is preserved.

Rationale: Typical adult ranges are about 7 to 20 mg/dL for BUN and about 0.6 to 1.2 mg/dL for creatinine (ranges vary by lab, age and muscle mass). BUN rises for reasons outside the kidney: blood in the GI tract is digested as protein and turned into urea, and dehydration or blood loss concentrates it. Creatinine is the more specific marker of kidney function, and here it is normal and unchanged from baseline, so this does not look like acute kidney injury. A BUN-to-creatinine ratio well above 20:1 fits a prerenal cause such as volume loss or GI bleeding. Creatinine comes from muscle, not the liver. The nurse keeps monitoring for ongoing bleeding (vital signs, stools, hemoglobin), intake and output, and repeat BUN and creatinine.

Answer: D. Report the findings to the health care provider and review the medication list for drugs that can harm the kidneys.

Rationale: A creatinine that doubles from baseline, together with urine output under 0.5 mL/kg/hr for 6 hours or more, meets common criteria (KDIGO) for acute kidney injury. The nurse reports this promptly so the provider can look for the cause, such as low volume, low blood pressure or obstruction. The nurse also reviews medications that can injure the kidneys or build up when they fail, including NSAIDs like ibuprofen, aminoglycosides, vancomycin and IV contrast, and clarifies doses with the provider and pharmacist. Giving an NSAID now could worsen the injury. Pushing 3 liters of fluid without an order can overload a client whose kidneys are not clearing fluid, and waiting a week is unsafe. IV contrast is avoided or used with precautions when kidney function is falling. Fluid, lab and imaging decisions follow the provider's orders and facility protocol.

Answer: A. "I will not take over-the-counter pain relievers like ibuprofen or naproxen unless my kidney doctor says it is okay."

Rationale: An eGFR of 15 to 29 mL/min/1.73 m² is stage 4 chronic kidney disease. At this level the kidneys cannot clear many drugs and minerals well. NSAIDs such as ibuprofen and naproxen reduce blood flow to the kidneys and can speed the decline, so the client should check with the provider before using any over-the-counter product. Magnesium-containing laxatives and antacids can cause high magnesium, and sodium phosphate enemas can cause dangerous phosphate and electrolyte shifts in kidney disease. Chronic kidney disease is not reversed by drinking more water; in later stages, fluid may even be limited. The client should follow the fluid, diet and medication plan set by the kidney care team.

Answer: C. Two to three soft stools a day and improved orientation.

Rationale: Ammonia builds up when the damaged liver cannot convert it to urea, and it contributes to hepatic encephalopathy (confusion, asterixis, drowsiness). Lactulose traps ammonia in the colon and removes it in the stool. The usual goal is about 2 to 3 soft stools a day, but the exact target is set by the provider. The most meaningful sign of success is improved mental status, because ammonia levels do not always match symptoms closely. Infrequent formed stools suggest the dose is not working. A rising ammonia level is the opposite of improvement. Too much lactulose causes diarrhea, dehydration and low potassium, and a potassium of 3.0 mEq/L is an adverse effect to report, not a sign of success; low potassium can actually worsen encephalopathy.

Answer: A. "Albumin helps hold fluid inside the blood vessels. When it is low, fluid leaks out into your abdomen and tissues."

Rationale: A typical adult serum albumin is about 3.5 to 5.0 g/dL (ranges vary by lab). Albumin is made by the liver, so it falls when the liver is badly damaged. Albumin creates oncotic pressure, the pull that keeps fluid inside the blood vessels. When it is low, fluid shifts into the tissues (edema) and the abdomen (ascites). In cirrhosis, raised pressure in the portal vein and sodium and water retention also add to ascites. The kidneys do not make albumin; protein lost in the urine would lower it, not raise it. Low albumin does not cause rapid clotting. The nurse monitors daily weight, abdominal girth, intake and output, and skin integrity, and follows the prescribed sodium restriction and diuretic plan.

Answer: C. Yellow sclera, itchy skin and dark tea-colored urine.

Rationale: A typical adult total bilirubin is about 0.3 to 1.2 mg/dL (ranges vary by lab). Jaundice usually becomes visible once the level is above about 2.5 to 3 mg/dL, first in the sclera and under the tongue, then the skin. Bile salts deposited in the skin cause itching (pruritus). When the liver cannot move bilirubin into bile, conjugated bilirubin is excreted by the kidneys, turning urine dark like tea, and stools may become pale or clay colored because less bilirubin reaches the gut. Pink urine with dark stools is the opposite pattern. Bluish lips signal low oxygen, and a raised red rash is not a typical bilirubin finding. Nursing care includes skin care for itching, cool baths, short nails and monitoring bilirubin and liver enzymes.

Answer: D. "The A1C shows your average glucose over about the last 2 to 3 months, and this result means your levels have been above goal much of that time."

Rationale: Hemoglobin A1C reflects the average blood glucose over roughly 2 to 3 months, the lifespan of red blood cells. A single normal morning reading does not cancel out high readings at other times of the day. The American Diabetes Association suggests an A1C goal below 7% for many nonpregnant adults, but goals are individualized: some clients have a lower target, and older or frail clients often have a higher one. An A1C of 8.9% is above the usual goal. Fasting is not needed for an A1C test. Conditions that change red blood cell lifespan, such as anemia, recent blood loss or transfusion, can make the A1C less reliable. The nurse can review home readings at different times of day and support the client in talking with the provider about the treatment plan.

Answer: B. Serum potassium, because insulin moves potassium into the cells and the level can fall quickly.

Rationale: In DKA, the serum potassium is often normal or high at first even though total body potassium is low, because acidosis and lack of insulin keep potassium outside the cells. Once insulin is given and the acidosis improves, potassium moves back into the cells, and the serum level can drop fast, causing dysrhythmias. That is why potassium is checked often (commonly every 1 to 2 hours early on, per protocol) and potassium is added to IV fluids once urine output is confirmed and the level falls into the range the protocol specifies. Many protocols, following ADA guidance, delay insulin if the potassium is below about 3.3 mEq/L. Sodium is also monitored but does not rise because of insulin. A1C changes over months and is not useful hour to hour. The nurse also tracks glucose hourly, the anion gap, cardiac rhythm and intake and output, and follows the facility's DKA protocol.

Answer: C. These results fit prediabetes, and lifestyle changes can lower the risk of developing type 2 diabetes.

Rationale: Using American Diabetes Association criteria, a fasting plasma glucose of 100 to 125 mg/dL or an A1C of 5.7% to 6.4% is prediabetes. Diabetes is diagnosed with a fasting glucose of 126 mg/dL or higher, an A1C of 6.5% or higher, a 2-hour glucose of 200 mg/dL or higher on an oral glucose tolerance test, or a random glucose of 200 mg/dL or higher with symptoms, usually confirmed by repeat testing. These results are above normal but below the diabetes cutoff, and they are not low. Teaching focuses on weight loss if appropriate, regular physical activity, healthy eating and follow-up testing; structured lifestyle programs have been shown to lower the risk of type 2 diabetes. Any medication decision belongs to the provider.

Answer: A. A client with type 2 diabetes receiving insulin whose bedside glucose is 42 mg/dL and who is hard to arouse.

Rationale: A glucose of 42 mg/dL with decreased level of consciousness is severe hypoglycemia and a medical emergency, because the brain depends on glucose. The nurse goes to this client first and follows the hypoglycemia protocol. A client who cannot safely swallow does not get oral glucose; treatment is usually IV dextrose or glucagon as ordered, then rechecking glucose in about 15 minutes and finding the cause. The other results are abnormal but stable and expected for each client's chronic condition: a creatinine of 4.2 mg/dL close to baseline in chronic kidney disease, a chronically low albumin in cirrhosis, and a mildly raised ALT (a typical upper limit is around 35 to 55 units/L, varying by lab) that matches earlier results in chronic hepatitis C. Stable chronic abnormal results are followed up, but they are not the first priority.