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2.7 Chloride (Cl)
Chloride is an electrolyte found outside the cell. Chloride is involved in fluid balance. The chloride test meas- ures the level of chloride in blood. The healthcare provider may order a chloride urine test or a skin sweat test.
The healthcare provider will likely order the chloride test along with tests for other electrolytes.
Why the Test Is Performed
The test screens for the underlying cause of confusion, muscle spasms, muscle weakness, difficulty breathing, metabolic alkalosis, kidney disorder, and adrenal gland disorder.
Before Administering the Test
Assess if the patient:• Is pregnant
• Has taken coumadin, aspirin, NSAIDs, corticosteroids, cholestyramine, diuretics, androgens, or estrogens
• Is dehydrated or overhydrated
How the Test Is Performed
A sample of blood is taken from the patient’s vein. The patient will experience a tight feeling when the tourni- quet is tightened, a pinch or nothing at all when the needle is inserted into the vein, and pressure when a gauze pad is pressed against the insertion site to stop bleeding. It can take up to 10 minutes for bleeding to stop if the patient is taking anticoagulants (aspirin, coumadin). A small bruise might appear at the insertion site, which could become swollen following this test. This is called phlebitis. Applying a warm compress several times a day will reduce the swelling.
Teach the Patient
Explain why the sample is taken and that the healthcare provider may ask the patient to refrain from taking coumadin, aspirin, NSAIDs, corticosteroids, cholestyramine, diuretics, androgens, or estrogens prior to the test.
Understanding the Test Results
The chloride test results are available quickly. The laboratory determines normal values based on calibration of testing equipment with a control test. Test results are reported as high, normal, or low based on the laboratory’s control test.
• Normal test results:
• Adults: 98 to 106 mEq/L
• Children: 90 to 110 mEq/L
• Newborns: 96 to 106 mEq/L
• Premature infants: 95 to 110 mEq/L
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Higher levels may indicate dehydration, anemia, kidney disease, hyperparathyroidism, or ingestion of salt.
Lower levels may indicate kidney failure, burns, Cushing’s syndrome, heart failure, vomiting, diabetic ketoacidosis, or SIADH.
Solved Problems
Electrolytes
2.1 What is an electrolyte?
Electrolytes are salts that are electrically charged ions used to maintain voltage across cell membranes. They carry electrical impulses within the body.
2.2 Name three electrolyte tests.
An electrolyte panel, basic metabolic panel, and comprehensive metabolic panel.
2.3 What electrolyte test measures only electrolytes in a sample of blood?
An electrolyte panel.
Calcium
2.4 Where is calcium stored in the body?
Calcium in the body is stored in bone with a minimum amount in blood.
2.5 What happens when there is too little calcium in the blood?
When there is too much phosphate (too little calcium) in blood, the parathyroid releases the parathyroid hormone (PTH) that stimulates osteoclast, breaking down bone to increase the calcium level in blood.
2.6 Name and describe two types of calcium tests.
The nonionized calcium test measures calcium attached to albumin in the blood and is affected by the amount of albumin in the blood. The ionized calcium test measures calcium not attached to albumin in the blood, and therefore is not affected by the amount of albumin in the blood.
2.7 What symptoms can be caused by either very high or very low calcium levels in the body?
Very high calcium levels in the blood can cause nausea, vomiting, bone pain, lack of appetite,
weakness, abdominal pain, constipation, and increased urination. Very low calcium levels in the blood can cause muscle spasms, depression, confusion, tingling around the mouth and fingers, and muscle cramping and twitching.
2.8 What should you assess in the patient before testing the patient’s calcium?
You should assess if the patient has:
• Taken milk, antacid, calcium salt, or calcium supplements 8 hours before administering the test, since this will affect the test result
• Eaten or drunk 12 hours before the test is administered
• Taken Diamox, estrogen, albuterol, corticosteroids, vitamin D, lithium, laxatives, aspirin, theophylline, or birth control pills, since these can affect the test result
• Had a blood transfusion recently 2.9 How are calcium test results reported?
Test results are reported as high, normal, or low based on the laboratory’s control test.
Magnesium
2.10 How does the body use magnesium?
Magnesium is used to transfer potassium and sodium in and out of cells and to activate nerves, muscles, and enzymes.
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2.11 Why is the test for magnesium given?
The magnesium test screens for the underlying cause of muscle weakness, muscle twitches, muscle irritability, arrhythmia, and the source of nausea, vomiting, low blood pressure, muscle weakness, and dizziness. The test also screens the effects of medication that causes changes in the level of
magnesium and the therapeutic treatment for high or low levels of magnesium.
2.12 What should the patient avoid taking prior to the magnesium test?
Explain not to take antacids, laxatives, Milk of Magnesia, diuretics, Epsom salts, or magnesium supplements three days before administering the test, since these can affect the test results.
Potassium
2.13 How does the body use potassium?
Potassium has multiple functions, including muscle contractions, neural transmission, and fluid balance.
2.14 What regulates potassium?
Potassium is excreted by the kidneys, which is regulated by the hormone aldosterone that is released by the adrenal glands.
2.15 Why is the potassium test ordered by the healthcare provider?
The potassium test screens for cell lysis syndrome. It also assesses the effects of total parenteral nutrition (TPN) being administered to the patient, adverse effect of diuretics, which can decrease potassium levels, the source of high blood pressure, and the effect of kidney dialysis.
2.16 What should you assess in the patient who is taking the potassium test?
Assess if the patient has:
• Taken potassium supplements
• Taken heparin, glucose, NSAIDs, antibiotics that contain potassium, natural licorice, corticosteroids, ACE inhibitors or insulin
• Experienced severe vomiting
• Improperly used laxatives
2.17 What might a high potassium value indicate?
A high potassium value might indicate heart attack, ingestion of too many potassium supplements, ingestion of ACE inhibitors, diabetic ketoacidosis, or kidney damage.
Sodium
2.18 What electrolyte has an inverse relationship with sodium?
Potassium.
2.19 Where is sodium stored in the body?
Sodium is a mineral stored outside the cell in blood and lymph fluid.
2.20 What regulates sodium in the body?
Aldosterone released by the adrenal glands.
2.21 Besides the electrolyte test, what other test might be ordered to measure sodium?
The healthcare provider may order a fractional excretion of sodium (FENa) urine test to determine the amount of sodium and creatinine in the urine.
2.22 What should be assessed before administering the sodium test?
Assess if the patient has:
• Elevated protein levels
• Received IV fluid containing sodium
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• High triglyceride levels
• Taken heparin, birth control pills, NSAIDs, antibiotics, tricyclic antidepressants, corticosteroids, lithium, or estrogen
2.23 Why would a healthcare provider order a sodium test?
A sodium test screens for adrenal gland diseases, electrolyte balance, water balance, and kidney disease.
2.24 What might a low sodium value indicate?
A low sodium value might indicate psychogenic polydipsia (drinking too much water), heart failure, vomiting, diarrhea, burns, SIADH, cirrhosis, malnutrition, and kidney disease.
2.25 Why would the sodium test be used to screen for kidney disease?
Sodium is excreted by the kidneys. Therefore, high sodium levels would be expected in kidney disease because the kidneys are not adequately excreting sodium.
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C H A P T E R 3
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