American Board of Internal Medicine (ABIM)
Subspecialty: Endocrinology, Diabetes &
Metabolism Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. A 45-year-old woman presents with heat intolerance, palpitations,
and unintentional weight loss. On examination, she has a diffusely
enlarged thyroid and a fine tremor. Her TSH is <0.01 mIU/L, free T4 is
elevated, and T3 is elevated. What is the most likely diagnosis?
A. Subacute thyroiditis
B. Graves disease
C. Toxic multinodular goiter
D. Hashimoto thyroiditis
Answer: B. Graves disease
Rationale: Graves disease is the most common cause of hyperthyroidism
in adults under 50 and is characterized by suppressed TSH, elevated
T4/T3, diffuse goiter, and symptoms like tremor, palpitations, and
weight loss.
2. Which antibody is most specific for Graves disease?
A. Anti-TPO antibody
B. Anti-thyroglobulin antibody
C. TSH receptor antibody (TRAb)
D. Anti-microsomal antibody
,Answer: C. TSH receptor antibody (TRAb)
Rationale: TRAb (also called thyroid-stimulating immunoglobulin) is
highly specific for Graves disease, leading to TSH receptor activation and
hyperthyroidism.
3. A 60-year-old man presents with fatigue, constipation, and weight
gain. His TSH is 12 mIU/L, free T4 is low. What is the most likely
diagnosis?
A. Subclinical hypothyroidism
B. Primary hypothyroidism
C. Central hypothyroidism
D. Euthyroid sick syndrome
Answer: B. Primary hypothyroidism
Rationale: Elevated TSH with low free T4 indicates primary
hypothyroidism, where the thyroid gland itself fails to produce adequate
hormone.
4. Which of the following is the most common cause of primary
hypothyroidism in the United States?
A. Iodine deficiency
B. Hashimoto thyroiditis
C. Subacute thyroiditis
D. Drug-induced hypothyroidism
Answer: B. Hashimoto thyroiditis
Rationale: Hashimoto thyroiditis is the most common cause of primary
, hypothyroidism in iodine-sufficient areas, associated with anti-TPO
antibodies.
5. A patient with type 1 diabetes presents with nausea, vomiting,
abdominal pain, and Kussmaul respirations. Labs show hyperglycemia
and metabolic acidosis. What is the most likely diagnosis?
A. Hyperosmolar hyperglycemic state
B. Diabetic ketoacidosis (DKA)
C. Lactic acidosis
D. Hypoglycemia
Answer: B. Diabetic ketoacidosis (DKA)
Rationale: DKA is characterized by hyperglycemia, metabolic acidosis,
ketonemia, and clinical features such as nausea, vomiting, and
Kussmaul respirations, mostly in type 1 diabetes.
6. Which electrolyte abnormality is most concerning during DKA
treatment with IV insulin?
A. Hypernatremia
B. Hypokalemia
C. Hypercalcemia
D. Hypophosphatemia
Answer: B. Hypokalemia
Rationale: Insulin drives potassium into cells, which can precipitate life-
threatening hypokalemia. Potassium should be monitored and replaced
during DKA treatment.
Subspecialty: Endocrinology, Diabetes &
Metabolism Questions And Correct Answers
(Verified Answers) Plus Rationales 2026 Q&A |
Instant Download Pdf
1. A 45-year-old woman presents with heat intolerance, palpitations,
and unintentional weight loss. On examination, she has a diffusely
enlarged thyroid and a fine tremor. Her TSH is <0.01 mIU/L, free T4 is
elevated, and T3 is elevated. What is the most likely diagnosis?
A. Subacute thyroiditis
B. Graves disease
C. Toxic multinodular goiter
D. Hashimoto thyroiditis
Answer: B. Graves disease
Rationale: Graves disease is the most common cause of hyperthyroidism
in adults under 50 and is characterized by suppressed TSH, elevated
T4/T3, diffuse goiter, and symptoms like tremor, palpitations, and
weight loss.
2. Which antibody is most specific for Graves disease?
A. Anti-TPO antibody
B. Anti-thyroglobulin antibody
C. TSH receptor antibody (TRAb)
D. Anti-microsomal antibody
,Answer: C. TSH receptor antibody (TRAb)
Rationale: TRAb (also called thyroid-stimulating immunoglobulin) is
highly specific for Graves disease, leading to TSH receptor activation and
hyperthyroidism.
3. A 60-year-old man presents with fatigue, constipation, and weight
gain. His TSH is 12 mIU/L, free T4 is low. What is the most likely
diagnosis?
A. Subclinical hypothyroidism
B. Primary hypothyroidism
C. Central hypothyroidism
D. Euthyroid sick syndrome
Answer: B. Primary hypothyroidism
Rationale: Elevated TSH with low free T4 indicates primary
hypothyroidism, where the thyroid gland itself fails to produce adequate
hormone.
4. Which of the following is the most common cause of primary
hypothyroidism in the United States?
A. Iodine deficiency
B. Hashimoto thyroiditis
C. Subacute thyroiditis
D. Drug-induced hypothyroidism
Answer: B. Hashimoto thyroiditis
Rationale: Hashimoto thyroiditis is the most common cause of primary
, hypothyroidism in iodine-sufficient areas, associated with anti-TPO
antibodies.
5. A patient with type 1 diabetes presents with nausea, vomiting,
abdominal pain, and Kussmaul respirations. Labs show hyperglycemia
and metabolic acidosis. What is the most likely diagnosis?
A. Hyperosmolar hyperglycemic state
B. Diabetic ketoacidosis (DKA)
C. Lactic acidosis
D. Hypoglycemia
Answer: B. Diabetic ketoacidosis (DKA)
Rationale: DKA is characterized by hyperglycemia, metabolic acidosis,
ketonemia, and clinical features such as nausea, vomiting, and
Kussmaul respirations, mostly in type 1 diabetes.
6. Which electrolyte abnormality is most concerning during DKA
treatment with IV insulin?
A. Hypernatremia
B. Hypokalemia
C. Hypercalcemia
D. Hypophosphatemia
Answer: B. Hypokalemia
Rationale: Insulin drives potassium into cells, which can precipitate life-
threatening hypokalemia. Potassium should be monitored and replaced
during DKA treatment.
