NCLEX-PN lab values practice questions

Question 1

The nurse is reviewing sodium imbalances with a student. For each finding, specify whether it belongs with a high sodium or with a low sodium.

Accepted Answer

Dry, sticky mucous membranes: High sodium; Headache with nausea: Low sodium; Confusion that came on over a day or two: Low sodium; Intense thirst: High sodium; Muscle cramps with a serum osmolality of 258: Low sodium; Flushed, dry skin: High sodium. Sodium decides where water sits, so every one of these rows is really about which way water is moving.

When the sodium is high the blood is too salty, so water is pulled out of the cells and into the circulation. The tissues dry out, which is the sticky mouth, the flushed dry skin and the thirst, and the brain shrinks slightly, which makes the client restless and agitated.

When the sodium is low the blood is too dilute, so water moves into the cells. The brain swells, and swelling in a space that cannot expand gives headache, nausea, confusion and eventually seizures.

The osmolality is the tidiest confirmation of all. A low osmolality means dilute blood, and dilute blood means a low sodium.

Question 2

The nurse is reinforcing teaching with a 33-year-old client with bipolar I disorder who takes lithium carbonate 450 mg orally at 0800 and 2000 and is due for a lithium level at the clinic laboratory tomorrow morning. Which of the following instructions should the nurse reinforce?

Accepted Answer

B: "Take your 2000 dose tonight as usual, and have the blood drawn at about 0800 tomorrow before your morning dose.". Lithium is a mood-stabilizing medicine used to treat bipolar disorder.

Lithium has a narrow therapeutic range, about 0.6 to 1.2 mEq/L for maintenance, and the ranges are set for a trough level drawn about 12 hours after the last dose. After each dose the level climbs for a few hours and then falls, so a sample drawn at the wrong time cannot be compared with the range.

For a client who takes doses at 0800 and 2000, the trough falls at about 0800 the next morning, just before the morning dose. The client takes the evening dose as usual and holds the morning dose until the blood has been drawn. A level drawn after the morning dose reads falsely high and could lead to an unneeded dose reduction and a relapse. A skipped evening dose reads falsely low and could lead to a dose increase and toxicity.

Question 3

A resident of a long-term care facility who has heart failure is due for furosemide 40 mg by mouth at 0900. This morning's potassium is 3.0 mEq/L, and she says her legs have been cramping since last night. Which of the following actions should the nurse take?

Accepted Answer

B: Withhold the furosemide and report the potassium level and the leg cramps to the registered nurse (RN). Furosemide is a loop diuretic. It stops the kidney from reabsorbing sodium and chloride in the loop of Henle, water follows the sodium out, and potassium is washed out into the urine along with it. That is why a client on furosemide has the potassium checked, and why a low potassium is the commonest problem the drug causes.

The normal potassium is 3.5 to 5.0 mEq/L, so 3.0 mEq/L is low. Potassium keeps muscle and nerve cells able to fire normally, and the leg cramps are the muscles showing it. The same shortage affects the heart muscle, where it can cause dangerous irregular rhythms, and in a client with heart failure, who may also take digoxin, that risk is higher still.

Giving another dose of furosemide now would push the potassium lower. So the dose is withheld and the result, with the cramps, goes to the registered nurse (RN), who contacts the provider. The provider decides whether the dose is changed and orders the potassium replacement and a recheck.

Question 4

During a home health visit, the nurse is reinforcing the dietitian's teaching with a 64-year-old client with stage 4 chronic kidney disease who wants to keep eating potatoes. The client's serum potassium is 5.3 mEq/L, and the dietitian has taught the client to leach potatoes, a method that lowers the potassium content of the potato before cooking. Place the following steps in the order the client should perform them.

Accepted Answer

1: Peel the potatoes and cut them into thin slices or small cubes; 2: Rinse the cut pieces under warm running water; 3: Boil the pieces in a large pot of unsalted water for about 10 minutes; 4: Drain the potatoes and discard the water they were boiled in; 5: Finish the potatoes by roasting, frying, or mashing them. Leaching works because potassium dissolves in water. Peeling removes the skin, which holds much of the potassium, and cutting the potato into thin slices or small cubes exposes far more surface for the potassium to move into the water. A rinse washes the potassium off the cut surfaces.

Boiling the pieces in a large volume of water draws more potassium out, and that water is thrown away, because the potassium is now in it. Only then are the potatoes roasted, fried, or mashed. This method lowers the potassium in potatoes by roughly half, which lets the client keep a favorite food in small portions while staying within the limit.

Question 5

A client is admitted with a small bowel obstruction. The client has a nasogastric tube to low intermittent suction, is NPO and has 0.9% sodium chloride infusing. The nurse collects data at 1000. Which of the following findings is the priority to report to the registered nurse (RN)?

Accepted Answer

C: A urine output of 20 mL in the past hour. A bowel obstruction is a partial or complete blockage that stops food, fluid and gas from moving normally through the intestine.

When the small bowel is blocked, fluid that would normally be absorbed builds up in the bowel above the blockage. The client also loses fluid through vomiting and the nasogastric tube. Together these drain the circulating blood volume quickly.

A urine output of 20 mL in an hour is below the minimum of 30 mL, which means the kidneys are not getting enough blood. Fluid balance is the priority, ahead of restoring a normal bowel pattern, because a falling circulating volume leads to shock and kidney injury. The nurse reports the low output so the fluid replacement can be adjusted, and continues to measure intake and output and vital signs.

Question 6

A 52-year-old client with a fasting glucose of 108 mg/dL on two occasions is scheduled for a 2-hour oral glucose tolerance test at the outpatient laboratory. The nurse is reinforcing the instructions for the test. Place the following steps in the order the client should complete them.

Accepted Answer

1: Fast for at least 8 hours before arriving at the laboratory; 2: Have a fasting blood sample drawn; 3: Drink a solution containing 75 g of glucose within 5 minutes; 4: Remain seated without eating, drinking, or smoking until the test is over; 5: Have a second blood sample drawn 2 hours after finishing the drink. An oral glucose tolerance test measures how well the body clears a standard load of glucose. A fasting glucose of 100 to 125 mg/dL is in the prediabetes range, and the test shows whether the client's response to glucose has already reached the diabetes range.

The client fasts for at least 8 hours so the starting value is a true fasting level, and that fasting sample is drawn before anything else. The client then drinks 75 g of glucose within 5 minutes so the timing is standard. Activity, food, drink, and smoking all change the glucose level, so the client stays seated and takes nothing until the 2-hour sample is drawn. A 2-hour value of 200 mg/dL or higher means diabetes, and 140 to 199 mg/dL means prediabetes.

Question 7

A client in a rehabilitation facility is recovering from extensive burns to the face and arms sustained 3 weeks ago. The client has lost 4 kg since the injury, the prealbumin is 12 mg/dL (120 mg/L) and the client has eaten less than a quarter of each meal for 3 days. At lunch the client pushes the tray away and says, "Why bother? I'm never going to look like myself again." Which action should the nurse take first?

Accepted Answer

C: Sit down with the client and explore what the client is feeling. A burn is an injury to the skin and deeper tissues caused by heat, chemicals, electricity or radiation.

Two problems are present, and they are linked. The client's nutrition is failing: a large burn can nearly double the need for calories and protein, and a 4-kg loss with a low prealbumin shows intake is far behind. But the client has also just said something that sounds like hopelessness, and the poor eating may be one sign of it.

The statement comes first. "Why bother?" from a client facing a permanent change in appearance can signal grief turning into depression, and it has to be explored before anything else will work. A client who sees no point in recovering will refuse the shake and the favorite foods just as the tray was refused. Sitting down and inviting the client to talk lets the nurse find out how deep the hopelessness goes, ask directly about thoughts of self-harm if needed, and report the statement and the poor intake to the registered nurse (RN). Nutrition support follows straight after.

Question 8

The nurse in a long-term care facility receives four laboratory results at the start of the shift. Which of the following should the nurse report to the registered nurse (RN) first?

Accepted Answer

A: Potassium 6.3 mEq/L. All four numbers are outside their ranges, so the sorting question is not which one is abnormal. It is which one can stop a heart before the shift is over.

A potassium of 6.3 is that one. Potassium is what lets heart muscle fire and then reset, and too much of it makes the reset fail. The rhythm goes first and the heart can arrest with very little warning, which is why the result goes straight to the registered nurse rather than into a written entry to be read later.

The other three are real and none of them changes in the next hour. A hemoglobin of 10.4 makes a resident tired. A urea of 28 is barely over. A white count of 12,200 says something is brewing and is worth reporting, in order, after the potassium.

Question 9

A 71-year-old client with acute kidney injury reports no bowel movement for 4 days. The serum creatinine is 4.2 mg/dL, and the urine output has been 15 to 20 mL/hr since admission. The nurse reviews the prescriptions for constipation before the evening medication pass. Which prescription should the nurse question?

Accepted Answer

A: Sodium phosphate enema 133 mL rectally once now. Acute kidney injury (AKI) is a sudden loss of kidney function that develops over hours to days.

The kidneys are the main route for removing phosphate, so a client with oliguric acute kidney injury already retains it, and the serum phosphorus is often above 4.5 mg/dL. A sodium phosphate enema delivers a large phosphate load, and some of it is absorbed through the bowel wall. With no way to excrete it, the phosphorus climbs higher, binds calcium, and lowers the calcium level, which can cause tetany and dysrhythmias. Phosphate can also deposit in the kidney tissue and add to the injury.

Checking whether a prescription is appropriate for the client is part of the nurse's role before any dose. The nurse holds the enema and contacts the provider for an alternative. Magnesium-based laxatives are avoided for the same reason, because the kidneys cannot clear magnesium either.

Question 10

A 66-year-old client with SIADH from a lung tumor was admitted 2 days ago with a serum sodium of 121 mEq/L and confusion, and the client has followed an 800-mL daily fluid restriction since admission. The nurse collects the morning data on day 3. For each finding, click to specify if the finding indicates that the client's condition has improved, has not changed, or has declined.

Accepted Answer

Oriented to person, place, and time: Improved; Serum sodium 129 mEq/L: Improved; Lung sounds clear in all fields, as on admission: Not changed; Urine output 1,100 mL in 24 hours, up from 600 mL on admission: Improved; Weight 1.5 kg (3.3 lb) less than on admission: Improved. In SIADH the kidneys hold on to water, so the body carries extra water that dilutes the sodium. Fluid restriction lets the kidneys slowly clear that water. When it works, the sodium rises, the weight falls as the extra water leaves, the urine output increases, and the brain recovers as the sodium returns toward normal.

This client shows every one of those changes. The sodium has risen from 121 to 129 mEq/L, about 4 mEq/L a day, which is a safe pace. The confusion has cleared, the weight is down by 1.5 kg, and the urine output has nearly doubled. The restriction is working, and it continues until the sodium is in the normal range of 135 to 145 mEq/L.

NCLEX-PN lab values practice questions.