Effect of herbal medicine on clinical laboratory testing MCQs With Answer

Introduction
This quiz collection focuses on the effect of herbal medicines on clinical laboratory testing, a critical topic for M.Pharm students preparing for practice and research. Herbal products can alter laboratory assays by pharmacodynamic effects (e.g., bleeding, hepatotoxicity), pharmacokinetic interactions (enzyme induction/inhibition), direct chemical interference (color, redox activity), and immunoassay cross-reactivity (notably biotin interference). Understanding these mechanisms helps pharmacists interpret unexpected laboratory results, advise patients about supplement use before testing, and anticipate potential adulteration or toxicity. The following 20 MCQs cover common herbal agents, their laboratory impacts, assay-specific interferences, and real-world clinical consequences to deepen your analytical skills in herbal and clinical laboratory interactions.

Q1. Which statement best describes how high-dose biotin supplements interfere with many modern immunoassays used in clinical laboratories?

• Biotin binds to assay antibodies and increases signal for all assays
• Excess free biotin competes with biotinylated assay components for streptavidin binding, causing falsely low results in sandwich assays and falsely high results in competitive assays
• Biotin oxidizes colorimetric substrates producing spurious color development
• Biotin chelates metal ions used in enzymatic reactions, permanently inactivating the enzymes

Correct Answer: Excess free biotin competes with biotinylated assay components for streptavidin binding, causing falsely low results in sandwich assays and falsely high results in competitive assays

Q2. Which herbal supplement is a well-known inducer of CYP3A4 and P‑glycoprotein that can lower plasma concentrations of many drugs and affect therapeutic drug monitoring?

• Ginkgo biloba
• St. John’s wort (Hypericum perforatum)
• Kava (Piper methysticum)
• Licorice (Glycyrrhiza glabra)

Correct Answer: St. John’s wort (Hypericum perforatum)

Q3. Which herbal product has been frequently associated with clinically significant hepatotoxicity and elevated transaminases in case reports and regulatory warnings?

• Green tea extract (Camellia sinensis) at high doses
• Ginseng (Panax ginseng)
• Ginger (Zingiber officinale)
• Chamomile (Matricaria chamomilla)

Correct Answer: Green tea extract (Camellia sinensis) at high doses

Q4. Which herbal medicine is most characteristically linked to platelet dysfunction and an increased bleeding tendency that may prolong bleeding-time based assays?

• St. John’s wort
• Ginkgo biloba
• Black cohosh
• Milk thistle

Correct Answer: Ginkgo biloba

Q5. A patient taking an herbal weight-loss supplement containing Ephedra (Ma Huang) has a positive amphetamine urine immunoassay. What is the most likely explanation?

• Contamination with benzodiazepines
• Cross-reactivity of ephedrine/related sympathomimetics with amphetamine immunoassays
• Hepatotoxic metabolites generating amphetamine-like signals
• Ephedra causes hemolysis that interferes with the assay

Correct Answer: Cross-reactivity of ephedrine/related sympathomimetics with amphetamine immunoassays

Q6. Polyphenolic antioxidants in some herbal extracts (e.g., green tea catechins, curcumin) can alter results of redox‑based clinical assays. What typical interference occurs in oxidase-based assays?

• Antioxidant activity reduces the oxidized detection product, causing falsely low results
• Polyphenols precipitate proteins leading to falsely high values
• They act as enzyme cofactors increasing assay sensitivity and results
• They chelate assay buffers producing random scatter without directional bias

Correct Answer: Antioxidant activity reduces the oxidized detection product, causing falsely low results

Q7. Which herbal supplement is most likely to decrease warfarin plasma concentrations and reduce INR via induction of hepatic metabolism?

• Garlic (Allium sativum)
• Ginseng (Panax ginseng)
• St. John’s wort (Hypericum perforatum)
• Dong quai (Angelica sinensis)

Correct Answer: St. John’s wort (Hypericum perforatum)

Q8. A patient reports taking kava for anxiety and presents with elevated ALT and AST. Which statement best describes this herb’s laboratory risk?

• Kava is hepatoprotective and lowers transaminases in all patients
• Kava has been linked to idiosyncratic hepatotoxicity and can cause clinically significant transaminase elevations
• Kava only interferes with coagulation assays but not liver enzymes
• Kava causes false-positive hepatitis serology by cross-reacting with viral antigens

Correct Answer: Kava has been linked to idiosyncratic hepatotoxicity and can cause clinically significant transaminase elevations

Q9. High-dose biotin ingestion prior to thyroid immunoassays can produce which apparent laboratory pattern?

• Falsely elevated TSH and low free T4 (apparent hypothyroidism)
• No effect on thyroid assays
• Falsely low TSH and falsely high free T4 (apparent hyperthyroidism)
• Only total T4 is affected while free T4 and TSH remain accurate

Correct Answer: Falsely low TSH and falsely high free T4 (apparent hyperthyroidism)

Q10. Aristolochic acid, found in some herbal weight‑loss and traditional remedies, produces a distinctive clinical laboratory syndrome. Which is characteristic?

• Acute hemolysis with elevated LDH but normal creatinine
• Progressive interstitial nephropathy with rising serum creatinine and anemia
• Marked hyperkalemia with metabolic acidosis only
• Isolated transaminase elevation without renal involvement

Correct Answer: Progressive interstitial nephropathy with rising serum creatinine and anemia

Q11. Topical application or ingestion of henna (Lawsonia inermis) can produce which laboratory-related adverse effect in susceptible individuals?

• Hemolytic anemia in individuals with glucose‑6‑phosphate dehydrogenase (G6PD) deficiency
• Persistent hyperbilirubinemia unrelated to hemolysis
• Marked leukocytosis with neutrophilia
• Prolonged PT/INR due to vitamin K antagonism

Correct Answer: Hemolytic anemia in individuals with glucose‑6‑phosphate dehydrogenase (G6PD) deficiency

Q12. Which herbal product contains coumarin‑like constituents and is known to potentiate warfarin anticoagulation, potentially increasing INR?

• Dong quai (Angelica sinensis)
• Ginseng (Panax ginseng)
• St. John’s wort (Hypericum perforatum)
• Black pepper (Piper nigrum)

Correct Answer: Dong quai (Angelica sinensis)

Q13. Which assay outcome can occur if a patient takes large biotin doses prior to a point-of-care urine hCG pregnancy test that uses a biotin‑streptavidin step?

• Biotin causes hematuria which invalidates the test
• Falsely positive hCG result in all immunoassays
• Falsely negative pregnancy test due to interference with sandwich format
• Urine creatinine is reduced, altering the test matrix and giving false positives

Correct Answer: Falsely negative pregnancy test due to interference with sandwich format

Q14. Excessive dietary intake of kelp (seaweed) supplements rich in iodine is most likely to cause which laboratory thyroid abnormality?

• Hypokalemia and low aldosterone
• Suppressed TSH with elevated free T4 (iodine‑induced thyrotoxicosis)
• False elevation of TSH by colorimetric interference
• Increased anti‑TPO antibody titers without hormone changes

Correct Answer: Suppressed TSH with elevated free T4 (iodine‑induced thyrotoxicosis)

Q15. The intense yellow pigment of turmeric (curcumin) can interfere with spectrophotometric laboratory assays. What is the typical mechanism of this interference?

• Curcumin forms insoluble complexes with assay proteins increasing turbidity
• Its strong absorbance at visible wavelengths adds background absorbance, producing falsely elevated results in colorimetric assays
• Curcumin enzymatically degrades assay substrates
• It chelates copper required in all spectrophotometric instruments

Correct Answer: Its strong absorbance at visible wavelengths adds background absorbance, producing falsely elevated results in colorimetric assays

Q16. Some so‑called “herbal” bodybuilding supplements have been adulterated with anabolic steroids. Which laboratory endocrine profile would you expect in a male taking such adulterated products?

• Increased endogenous LH and FSH with low serum testosterone
• Markedly elevated thyroid hormones but normal gonadotropins
• Elevated serum total testosterone with suppressed LH and FSH
• Only prolactin is increased while all other hormones remain normal

Correct Answer: Elevated serum total testosterone with suppressed LH and FSH

Q17. Which widely consumed culinary herb/supplement is known to prolong platelet function analyzer (PFA‑100) closure time and thereby affect platelet function testing?

• Garlic (Allium sativum)
• Echinacea
• St. John’s wort
• Milk thistle

Correct Answer: Garlic (Allium sativum)

Q18. Which herbal toxin is classically associated with progressive renal failure due to interstitial fibrosis and is a recognized cause of urothelial carcinoma in exposed patients?

• Gossypol from cottonseed
• Aristolochic acid from Aristolochia species
• Digitoxin from Digitalis species
• Camphor from Cinnamomum camphora

Correct Answer: Aristolochic acid from Aristolochia species

Q19. Chronic ingestion of licorice (Glycyrrhiza glabra) may produce a characteristic electrolyte and blood‑pressure profile detectable in laboratory testing. Which pattern is typical?

• Hyponatremia with high aldosterone and high renin
• Hypokalemia with hypertension and low renin (pseudoaldosteronism)
• Hyperkalemia with metabolic acidosis
• Isolated hypernatremia without blood‑pressure changes

Correct Answer: Hypokalemia with hypertension and low renin (pseudoaldosteronism)

Q20. Gymnema sylvestre is used as a herbal antidiabetic. What laboratory or clinical monitoring issue may arise when a patient taking conventional antidiabetic drugs also uses Gymnema?

• It causes assay cross‑reactivity producing false hyperglycemia on point‑of‑care meters
• It can potentiate hypoglycemic effects, increasing the risk of clinically significant low blood glucose
• It raises hemoglobin A1c independently of glucose levels
• It causes persistent glucosuria without changes in blood glucose

Correct Answer: It can potentiate hypoglycemic effects, increasing the risk of clinically significant low blood glucose

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