NSG 550 EXAM 2: (Latest 2026/2027 Update) Pulmonary Diagnostics,
Tumor Markers, & Lab Interpretation | Q&A | Grade A | 100% Correct
(Verified Answers) – Nursing Program
Subject: NSG 550 – Advanced Diagnostics / Pulmonary & Laboratory Medicine
Source: NSG 550 EXAM 2 Blueprint 2026/2027 Format: Q&A Guide with Rationale | Verified Grade A
1. What is alpha-1 antitrypsin (AAT) and what is its clinical significance?
Correct Answer: A serum protein produced by the liver normally found in the lungs that inhibits proteolytic
enzymes of white cells from lysing lung tissue; genetic deficiency of this protein can cause emphysema
1. AAT deficiency is an autosomal codominant disorder; most common in individuals of Northern European descent
(PiZZ phenotype).
2. Deficiency leads to unopposed neutrophil elastase activity → destruction of alveolar walls → panacinar emphysema
(basilar predominance).
3. Associated with liver disease (cirrhosis, hepatocellular carcinoma).
2. What is angiotensin-converting enzyme (ACE) and its clinical significance?
Correct Answer: An enzyme found on the surface of blood vessels in the lungs and other tissues with vasopressive
action
1. ACE converts angiotensin I to angiotensin II (potent vasoconstrictor).
2. Serum ACE is a biomarker for sarcoidosis (elevated in 60% of active cases).
3. ACE inhibitors lower blood pressure by blocking this enzyme.
3. What are cancer tumor markers used for clinically?
Correct Answer: Screen for early cancer, measurement of initial tumor burden, measure of response to anti-cancer
therapy, detection of recurrent cancer
1. Tumor markers are not generally used for primary screening (except PSA, AFP).
2. Serial monitoring of tumor markers (CEA, CA19-9, CA125, CA15-3) tracks treatment response.
3. Rising levels after treatment suggest recurrence before clinical symptoms.
4. What is carboxyhemoglobin (COHb) and what do the levels indicate?
Correct Answer: A stable complex of hemoglobin and carbon monoxide that prevents normal oxygen uptake in
the blood; 10-20% = symptoms of carbon monoxide poisoning; 30% = severe carbon monoxide poisoning; 50-80%
= deadly
1. CO binds to hemoglobin with 200x affinity of oxygen → left shift of ODC → impaired oxygen delivery.
2. Pulse oximetry is unreliable in CO poisoning (normal SpO2 despite low SaO2).
3. Treatment: 100% O2 via NRB (half-life 4-6h) or hyperbaric O2 (half-life 1-2h).
5. What is D-dimer and is it specific or sensitive?
Correct Answer: Degradation product of cross-linked fibrin; sensitive (highly sensitive, low specificity) — NOT
SPECIFIC
1. D-dimer is elevated in conditions with clot formation and fibrinolysis (DVT, PE, surgery, trauma, cancer, pregnancy,
inflammation).
2. High sensitivity (95%+) makes it useful as a rule-out test for VTE in low-risk patients.
3. Low specificity (30-40%) means positive D-dimer requires confirmatory imaging (ultrasound, CTA).
Tumor Markers, & Lab Interpretation | Q&A | Grade A | 100% Correct
(Verified Answers) – Nursing Program
Subject: NSG 550 – Advanced Diagnostics / Pulmonary & Laboratory Medicine
Source: NSG 550 EXAM 2 Blueprint 2026/2027 Format: Q&A Guide with Rationale | Verified Grade A
1. What is alpha-1 antitrypsin (AAT) and what is its clinical significance?
Correct Answer: A serum protein produced by the liver normally found in the lungs that inhibits proteolytic
enzymes of white cells from lysing lung tissue; genetic deficiency of this protein can cause emphysema
1. AAT deficiency is an autosomal codominant disorder; most common in individuals of Northern European descent
(PiZZ phenotype).
2. Deficiency leads to unopposed neutrophil elastase activity → destruction of alveolar walls → panacinar emphysema
(basilar predominance).
3. Associated with liver disease (cirrhosis, hepatocellular carcinoma).
2. What is angiotensin-converting enzyme (ACE) and its clinical significance?
Correct Answer: An enzyme found on the surface of blood vessels in the lungs and other tissues with vasopressive
action
1. ACE converts angiotensin I to angiotensin II (potent vasoconstrictor).
2. Serum ACE is a biomarker for sarcoidosis (elevated in 60% of active cases).
3. ACE inhibitors lower blood pressure by blocking this enzyme.
3. What are cancer tumor markers used for clinically?
Correct Answer: Screen for early cancer, measurement of initial tumor burden, measure of response to anti-cancer
therapy, detection of recurrent cancer
1. Tumor markers are not generally used for primary screening (except PSA, AFP).
2. Serial monitoring of tumor markers (CEA, CA19-9, CA125, CA15-3) tracks treatment response.
3. Rising levels after treatment suggest recurrence before clinical symptoms.
4. What is carboxyhemoglobin (COHb) and what do the levels indicate?
Correct Answer: A stable complex of hemoglobin and carbon monoxide that prevents normal oxygen uptake in
the blood; 10-20% = symptoms of carbon monoxide poisoning; 30% = severe carbon monoxide poisoning; 50-80%
= deadly
1. CO binds to hemoglobin with 200x affinity of oxygen → left shift of ODC → impaired oxygen delivery.
2. Pulse oximetry is unreliable in CO poisoning (normal SpO2 despite low SaO2).
3. Treatment: 100% O2 via NRB (half-life 4-6h) or hyperbaric O2 (half-life 1-2h).
5. What is D-dimer and is it specific or sensitive?
Correct Answer: Degradation product of cross-linked fibrin; sensitive (highly sensitive, low specificity) — NOT
SPECIFIC
1. D-dimer is elevated in conditions with clot formation and fibrinolysis (DVT, PE, surgery, trauma, cancer, pregnancy,
inflammation).
2. High sensitivity (95%+) makes it useful as a rule-out test for VTE in low-risk patients.
3. Low specificity (30-40%) means positive D-dimer requires confirmatory imaging (ultrasound, CTA).
