ABIM Endocrinology common mistakes
ABIM Endocrinology · Understand the traps and how to avoid them.
Diagnosing diabetes from a single HbA1c in a patient with iron-deficiency anemia, CKD, or a hemoglobin variant, without confirming with plasma glucose.
HbA1c reflects average glycemia only when red-cell turnover and hemoglobin are normal; anemia, CKD, and hemoglobinopathies distort the result, and candidates anchor on one familiar number.
What to do instead
Confirm an abnormal HbA1c with fasting plasma glucose, 2-hour OGTT, or random glucose plus symptoms; if discordant, use glucose-based criteria and document the assay limitation.
Intensifying insulin in a hospitalized patient with CKD and recurrent hypoglycemia without reviewing insulin clearance and sulfonylurea use.
Renal impairment reduces insulin clearance and sulfonylureas accumulate; candidates react to the glucose number instead of the medication and renal context.
What to do instead
Review all glucose-lowering medications, renal function, and nutrition; hold or modify sulfonylureas and adjust insulin, using a hypoglycemia protocol and avoiding reflexive dose increases.
Labeling a patient statin-intolerant after one episode of muscle aching without documenting creatine kinase, temporal relationship, or a structured rechallenge.
Muscle symptoms are common and nonspecific; candidates accept the intolerance label and forgo proven ASCVD risk reduction.
What to do instead
Assess CK if myopathy is suspected, review drug interactions, and try an alternate statin or dose; use a stepwise intolerance approach and nonstatin therapy when needed.
Treating a high TSH drawn during acute illness as primary hypothyroidism without repeating TSH and interpreting free T4.
Nonthyroidal illness causes transient TSH and T4 abnormalities; candidates pattern-match the number to hypothyroidism instead of the clinical context.
What to do instead
Defer treatment unless overt hypothyroidism is confirmed; repeat TSH and free T4 after recovery, and use age-appropriate TSH ranges.
Starting levothyroxine for subclinical hypothyroidism based on one TSH of 5-10 without confirming persistence or considering age and symptoms.
TSH fluctuates and age shifts the upper reference limit; candidates treat a single borderline value rather than a persistent biochemical pattern.
What to do instead
Repeat TSH in 6-12 weeks with free T4; consider age-specific ranges and treat only when the elevation is persistent and clinically appropriate.
In central hypothyroidism, starting levothyroxine before assessing cortisol and adrenal reserve.
Thyroid hormone increases cortisol clearance and can precipitate adrenal crisis; candidates focus on the low free T4 and miss the required treatment sequence.
What to do instead
Check morning cortisol or perform cosyntropin stimulation first; if adrenal insufficiency is present, give glucocorticoid replacement before levothyroxine.
Diagnosing prolactinoma from a mildly elevated prolactin without excluding stalk effect, medications, or macroprolactin.
Dopamine blockade and stalk compression raise prolactin modestly, and macroprolactin causes assay false elevation; candidates jump to imaging and treatment.
What to do instead
Review medications, repeat and dilute prolactin, and consider PEG precipitation; if stalk effect is suspected, assess pituitary function and obtain MRI rather than treating as prolactinoma.
Diagnosing PCOS in a woman with oligomenorrhea without excluding pregnancy, thyroid dysfunction, hyperprolactinemia, and nonclassic congenital adrenal hyperplasia.
PCOS is a diagnosis of exclusion; candidates apply Rotterdam criteria without completing the exclusion workup.
What to do instead
Document pregnancy test, TSH, prolactin, and androgen evaluation; check 17-hydroxyprogesterone when nonclassic CAH is possible, then apply PCOS criteria.
Using a total calcium result without albumin correction or ionized calcium in a patient with hypoalbuminemia.
Total calcium falls with albumin while ionized calcium may be normal; candidates treat the number as true hypocalcemia.
What to do instead
Correct total calcium for albumin or measure ionized calcium; interpret with PTH, magnesium, vitamin D, and renal function before treating.
Starting osteoporosis medication without checking secondary causes, vitamin D status, and fracture risk.
Glucocorticoids, hyperparathyroidism, malabsorption, and vitamin D deficiency alter management; candidates prescribe the first drug instead of completing the workup.
What to do instead
Obtain calcium, vitamin D, PTH, TSH, CBC, renal and liver function, and celiac screening when indicated; calculate fracture risk and correct reversible causes before choosing therapy.