NSG 550 Diagnostics Exam 1: (Latest 2026/2027 Update) Lab Values &
Diagnostic Testing | Q&A | Grade A | 100% Correct (Verified Answers) –
Nursing Program
Subject: NSG 550 – Advanced Diagnostics / Laboratory Interpretation
Source: NSG 550 Diagnostics Exam 1 Blueprint 2026/2027
Format: Q&A Guide with Rationale | Verified Grade A
1. What is the precision of a test?
Correct Answer: Ability of the test to yield the same results on multiple trials using the same sample
(repeatability/reliability)
1. Precision is about consistency; low precision = high random error.
2. A test can be precise but not accurate (systematic bias).
3. Laboratory quality control ensures precision through daily calibration and duplicate testing.
2. What is the accuracy of a test?
Correct Answer: Does the test measure what it is designed to measure (validity)
1. Accuracy compares test result to gold standard; includes both sensitivity and specificity.
2. Systematic error reduces accuracy; random error reduces precision.
3. High accuracy ensures correct classification of disease status.
3. What does sensitivity measure?
Correct Answer: Determines who has the disease; highly sensitive test gives low false negatives
1. Sensitivity = true positives / (true positives + false negatives).
2. High sensitivity (SnOUT): a negative result rules out disease.
3. Used for screening tests (e.g., HIV ELISA, D-dimer).
4. What does specificity measure?
Correct Answer: Determines who does NOT have the disease; highly specific test gives low false positives
1. Specificity = true negatives / (true negatives + false positives).
2. High specificity (SpPIN): a positive result rules in disease.
3. Used for confirmatory tests (e.g., HIV Western blot).
5. What is the Choosing Wisely Campaign?
Correct Answer: Developed by the American Board of Internal Medicine to promote conversations between
physicians and patients, helping patients choose care that is: supported by evidence, not duplicative, free from
harm, and truly necessary
1. Over 80 specialty societies have published "Choosing Wisely" lists.
2. Examples: avoid imaging for uncomplicated headache, avoid antibiotics for viral URI.
3. Goal: reduce low-value care and prevent patient harm.
, 6. What is ACTH (adrenocorticotropic hormone) and its function?
Correct Answer: Stimulates adrenal cortex to release glucocorticoids (cortisol); response to stress, fights infection,
regulates blood sugar, blood pressure, and metabolism; made by the pituitary gland
1. ACTH is secreted by anterior pituitary in response to CRH (hypothalamus).
2. Cortisol has diurnal variation (highest 6-8am).
3. ACTH stimulation test diagnoses adrenal insufficiency.
7. What labs should be drawn when looking for endocrine disease process?
Correct Answer: ACTH and cortisol
1. Simultaneous ACTH and cortisol differentiate primary vs secondary adrenal disorders.
2. High ACTH + low cortisol = primary adrenal insufficiency (Addison's).
3. Low ACTH + high cortisol = Cushing syndrome (adrenal/ectopic).
8. What is the difference between Cushing's disease and Cushing's syndrome?
Correct Answer: Cushing's disease: too much ACTH and cortisol (pituitary adenoma); Cushing's syndrome: too
much cortisol (any cause: adrenal tumor, exogenous steroids, ectopic ACTH)
1. Cushing's disease accounts for 70-80% of endogenous Cushing syndrome.
2. Distinguish with ACTH level: high in Cushing disease, low in adrenal tumor.
3. Dexamethasone suppression test used for diagnosis.
9. What is Addison's disease?
Correct Answer: A condition that occurs when the adrenal glands do not produce enough cortisol or aldosterone
(primary adrenal insufficiency)
1. Labs: low cortisol, high ACTH, hyperkalemia, hyponatremia.
2. Autoimmune destruction most common cause (80%).
3. Treatment: hydrocortisone and fludrocortisone.
10. High ACTH and high cortisol indicate what?
Correct Answer: Cushing's disease (pituitary adenoma) or ectopic ACTH production (e.g., small cell lung cancer)
1. High ACTH excludes primary adrenal tumor (which would suppress ACTH).
2. Pituitary MRI and CRH stimulation test differentiate pituitary vs ectopic.
3. Ectopic ACTH often associated with hypokalemia, metabolic alkalosis.
11. High ACTH and low cortisol indicate what?
Correct Answer: Addison's disease (primary adrenal insufficiency)
1. Low cortisol with inappropriately high ACTH indicates adrenal gland failure.
2. ACTH stimulation test shows no cortisol response.
3. Other causes: autoimmune, TB, metastatic cancer, hemorrhage.
12. Low ACTH and high cortisol indicate what?
Correct Answer: Cushing's syndrome (adrenal tumor or exogenous steroids)
1. Low ACTH with high cortisol suggests cortisol is from adrenal source or iatrogenic.
2. Adrenal imaging (CT) identifies tumor.
3. Exogenous steroids (prednisone) cause same pattern.
13. Low ACTH and low cortisol indicate what?
Correct Answer: Hypopituitarism (secondary adrenal insufficiency)
1. Secondary AI: pituitary fails to produce ACTH; aldosterone preserved.
2. Common causes: pituitary tumor, Sheehan syndrome, traumatic brain injury.
3. ACTH stimulation test: delayed or absent cortisol rise.
Diagnostic Testing | Q&A | Grade A | 100% Correct (Verified Answers) –
Nursing Program
Subject: NSG 550 – Advanced Diagnostics / Laboratory Interpretation
Source: NSG 550 Diagnostics Exam 1 Blueprint 2026/2027
Format: Q&A Guide with Rationale | Verified Grade A
1. What is the precision of a test?
Correct Answer: Ability of the test to yield the same results on multiple trials using the same sample
(repeatability/reliability)
1. Precision is about consistency; low precision = high random error.
2. A test can be precise but not accurate (systematic bias).
3. Laboratory quality control ensures precision through daily calibration and duplicate testing.
2. What is the accuracy of a test?
Correct Answer: Does the test measure what it is designed to measure (validity)
1. Accuracy compares test result to gold standard; includes both sensitivity and specificity.
2. Systematic error reduces accuracy; random error reduces precision.
3. High accuracy ensures correct classification of disease status.
3. What does sensitivity measure?
Correct Answer: Determines who has the disease; highly sensitive test gives low false negatives
1. Sensitivity = true positives / (true positives + false negatives).
2. High sensitivity (SnOUT): a negative result rules out disease.
3. Used for screening tests (e.g., HIV ELISA, D-dimer).
4. What does specificity measure?
Correct Answer: Determines who does NOT have the disease; highly specific test gives low false positives
1. Specificity = true negatives / (true negatives + false positives).
2. High specificity (SpPIN): a positive result rules in disease.
3. Used for confirmatory tests (e.g., HIV Western blot).
5. What is the Choosing Wisely Campaign?
Correct Answer: Developed by the American Board of Internal Medicine to promote conversations between
physicians and patients, helping patients choose care that is: supported by evidence, not duplicative, free from
harm, and truly necessary
1. Over 80 specialty societies have published "Choosing Wisely" lists.
2. Examples: avoid imaging for uncomplicated headache, avoid antibiotics for viral URI.
3. Goal: reduce low-value care and prevent patient harm.
, 6. What is ACTH (adrenocorticotropic hormone) and its function?
Correct Answer: Stimulates adrenal cortex to release glucocorticoids (cortisol); response to stress, fights infection,
regulates blood sugar, blood pressure, and metabolism; made by the pituitary gland
1. ACTH is secreted by anterior pituitary in response to CRH (hypothalamus).
2. Cortisol has diurnal variation (highest 6-8am).
3. ACTH stimulation test diagnoses adrenal insufficiency.
7. What labs should be drawn when looking for endocrine disease process?
Correct Answer: ACTH and cortisol
1. Simultaneous ACTH and cortisol differentiate primary vs secondary adrenal disorders.
2. High ACTH + low cortisol = primary adrenal insufficiency (Addison's).
3. Low ACTH + high cortisol = Cushing syndrome (adrenal/ectopic).
8. What is the difference between Cushing's disease and Cushing's syndrome?
Correct Answer: Cushing's disease: too much ACTH and cortisol (pituitary adenoma); Cushing's syndrome: too
much cortisol (any cause: adrenal tumor, exogenous steroids, ectopic ACTH)
1. Cushing's disease accounts for 70-80% of endogenous Cushing syndrome.
2. Distinguish with ACTH level: high in Cushing disease, low in adrenal tumor.
3. Dexamethasone suppression test used for diagnosis.
9. What is Addison's disease?
Correct Answer: A condition that occurs when the adrenal glands do not produce enough cortisol or aldosterone
(primary adrenal insufficiency)
1. Labs: low cortisol, high ACTH, hyperkalemia, hyponatremia.
2. Autoimmune destruction most common cause (80%).
3. Treatment: hydrocortisone and fludrocortisone.
10. High ACTH and high cortisol indicate what?
Correct Answer: Cushing's disease (pituitary adenoma) or ectopic ACTH production (e.g., small cell lung cancer)
1. High ACTH excludes primary adrenal tumor (which would suppress ACTH).
2. Pituitary MRI and CRH stimulation test differentiate pituitary vs ectopic.
3. Ectopic ACTH often associated with hypokalemia, metabolic alkalosis.
11. High ACTH and low cortisol indicate what?
Correct Answer: Addison's disease (primary adrenal insufficiency)
1. Low cortisol with inappropriately high ACTH indicates adrenal gland failure.
2. ACTH stimulation test shows no cortisol response.
3. Other causes: autoimmune, TB, metastatic cancer, hemorrhage.
12. Low ACTH and high cortisol indicate what?
Correct Answer: Cushing's syndrome (adrenal tumor or exogenous steroids)
1. Low ACTH with high cortisol suggests cortisol is from adrenal source or iatrogenic.
2. Adrenal imaging (CT) identifies tumor.
3. Exogenous steroids (prednisone) cause same pattern.
13. Low ACTH and low cortisol indicate what?
Correct Answer: Hypopituitarism (secondary adrenal insufficiency)
1. Secondary AI: pituitary fails to produce ACTH; aldosterone preserved.
2. Common causes: pituitary tumor, Sheehan syndrome, traumatic brain injury.
3. ACTH stimulation test: delayed or absent cortisol rise.
