July 27, 2017
Drugs Minimize

Drugs which interfere with Endocrine Tests

Hormone

Physiological increase

Physiological decrease

Analytical interference

Prolactin

SSRI antidepressants, anti-psychotic agents (Phenothiazines, Benzodiazepines,
& Butyrophenones), Bezafibrate, Tricyclic antidepressants (rare), MOA inhibitors, Metoclopramide, Omeprazole & H2 antagonists,   Sulpiride, Trimethoprim, Verapamil, opiates, Cimetidine, methyl DOPA, high dose oestrogens, 

Bromocriptine & other dopamine agonists, Lisuride, Pergolide, LevoDOPA, Clonidine, Carbamazepine, Phenytoin

macro-forms of prolactin

Growth hormone

Fenfluramine,
Amino-acids,
Clonidine,
Glucagon,
Indomethacin

alpha-blockers,
serotonin antagonists,
Chlorpromazine,
Corticosteroids,
Pyridostigmine,
Pirenzepine

GH assays may give different values following stimulation tests since there is differential clearance of the GH isoforms. The specific GH assays eg DELFIA may give slightly raised values due to the delayed clearance of the 22kDa isoform.

ACTH

Amphetamines,
Metyrapone

Glucocorticoids,
Cyproterone acetate,
Clonidine

 

Gonadotropins

Phenytoin,
Primidone,
Phenobarbitone

Sex hormones,
Opioids

hCG (Assay dependent effect)

Vasopressin & Oxytocin

potentially any drug, but commonly:
Sulphonylureas,
Carbamazepine,
MAO inhibitors,
thiazide diuretics esp Chlorothiazide
Lithium & Demeclocycline 2ndary to development of nephrogenic DI

Ethanol,
Phenytoin,
Some opioids

 

Thyroid gland dysfunction

Thyrotoxicosis:
Amiodarone
Iodine
Lithium (rarely)

Hypothyroidism:
Potassium perchlorate,
Carbimazole,
Sulphonylureas,
Phenylbutazone,
Aminoglutethimide,
Lithium,
Amiodarone

 

TSH

Sertraline (? only with thyroxine replacement)

Thyroxine,
Corticosteroids

 

Thyroxine & tri-iodothyronine

1: T4 increased (& T3 lowered) by amiodarone and propranolol (at doses greater than 160 mg/d)

2: Rare cases of Lithium induced hyperthyroidism have occurred

1: T3 & T4 are lowered by displacement from binding proteins by: salicylates, NSAIDs, and anticonvulsants (but not Valproate)

2: Thyroid hormones may be cleared faster and lowered by hepatic enzyme inducing drugs

3: Lithium may reduce T4 and T3 secretion by the thyroid gland and cause primary hypothyroidism

There are several assay-specific interferences with free thyroid hormones assays.
Some patients have been reported with antibodies directed against thyroid hormones

Thyroid binding globulin (TBG)

oestrogens,
Heroine & Methadone,
Clofibrate

androgens

 

Parathyroid hormone

Lithium

Diltiazem,
Vinblastine,
Colchicine

 

Catecholamines

all alpha-adrenergic stimulants,
Methyl DOPA,
small increase in nor-adrenaline with beta-blockers,
increase in metanephrines with MAO inhibitors.

alpha- & beta-blockers

alpha-methyl DOPA
Labetalol

5-HIAA (5-hydroxy-indole-acetic acid)

Increased secretion due to serotonin containing foods eg aubergines (eggplants), avocados, bananas, pineapples, plums, walnuts or the effects of some drugs eg paracetamol, caffeine, fluorouracil, melphalan, reserpine.

Chlorpromazine, Imipramine, Isoniazid, MAO inhibitors, L-DOPA, methyl DOPA, phenothiazines, Promethazine

 

Cortisol

Tetracosactrin "Synacthen" (R)
Glucagon

Metyrapone,
Aminoglutethimide,
Ketoconazole

Prednisolone

Cortisol binding globulin (CBG)

oestrogens
anti-convulsants

 

 

Aldosterone

Primary: mimicked by liquorice & Carbenoxolone
Secondary: oral contraceptives,
thiazides,
Minoxidil

Heparin,
beta-blockers,
ACE inhibitors
Calcium channel antagonists

 

Plasma renin activity

diuretics,
ACE inhibitors,
Minoxidil
calcium channel antagonists

beta-blockers,
Clonidine,
Reserpine

 

Oestradiol

anabolic steroids,
Carbamazepine,
Cimetidine,
Clomiphene,
DHEA,
Tamoxifen

gonadotropin-releasing hormone agonists,
Danazol

non-human oestrogens in HRT preparations

Testosterone

anabolic steroids,
Bromocriptine,
Cimetidine,
Finasteride (> 50mg/day),
Flutamide
Tamoxifen

gonadotropin-releasing hormone agonists,
Carbamazepine,
Digoxin,
Tetracycline (20%),
Sulphasalazine (oligospermia),
Cyproterone acetate
Females,
Danazol,
Dexamethasone,
Spironolactone

 

Sex hormone binding globulin (SHBG)

oral oestrogens
hyperthyroidism
Diazoxide, Metformin
Tamoxifen

oral androgens
anti-convulsants
hypothyroidism
anabolic steroids
Danazol

 

References

  • Baylis PH. Drug-induced endocrine disorders. Adverse Drug Reaction Bulletin 1986;116:432-435.
  • Vanderpump MPJ, Tunbridge WMG. The effect of drugs on endocrine function. Clin Endocrinol (Oxf) 1993;39:389-397.
  • Young DS. Effects of drugs on clinical laboratory tests. AACC press, Washington. 4th edit, 1995.
  

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