A 45-year-old woman presents with fatigue, weight gain, and constipation. Laboratory tests reveal high TSH and low free T4 levels. What is the most likely diagnosis?

Correct Answer: A

Rationale: The most likely diagnosis is A: Hypothyroidism. High TSH and low free T4 levels indicate primary hypothyroidism. Elevated TSH is a compensatory response by the pituitary gland to stimulate the thyroid to produce more thyroid hormones, but the thyroid gland is unable to do so effectively, resulting in low free T4 levels. Fatigue, weight gain, and constipation are classic symptoms of hypothyroidism. - B: Hyperthyroidism is characterized by low TSH and high free T4 levels, opposite of the lab results presented. - C: Thyroiditis may initially present with high or low thyroid hormone levels, but the combination of high TSH and low free T4 levels is more indicative of hypothyroidism. - D: Thyroid cancer typically does not cause abnormal thyroid hormone levels; it is more commonly associated with thyroid nodules or masses.

Correct Answer: A

Rationale: The correct answer is A: Hypothyroidism. The patient's symptoms of fatigue, weight gain, and cold intolerance are classic signs of hypothyroidism. Elevated TSH and low free T4 levels indicate primary hypothyroidism. TSH is high due to the pituitary gland trying to stimulate the thyroid gland to produce more thyroid hormones, but the thyroid gland is unable to do so. Hyperthyroidism (choice B) would present with opposite symptoms and lab values. Thyroiditis (choice C) typically presents with transient hyperthyroidism followed by hypothyroidism. Thyroid cancer (choice D) is less common and typically does not present with these typical hypothyroid symptoms and lab findings.

Correct Answer: D

Rationale: The correct answer is D: Crohn's disease flare. Given the patient's history of Crohn's disease, symptoms of abdominal pain, diarrhea, weight loss, and abnormal lab findings (low hemoglobin, elevated ESR) are indicative of a flare-up of Crohn's disease. This is supported by the clinical presentation and the lab results. Ulcerative colitis (A) presents differently with rectal bleeding and mucous diarrhea. Irritable bowel syndrome (B) does not typically cause weight loss or abnormal lab findings. Celiac disease (C) would present with malabsorption symptoms and specific antibodies, not consistent with this patient's presentation. Crohn's disease flare (D) is the most likely diagnosis based on the information provided.

Correct Answer: A

Rationale: The most likely diagnosis for the 45-year-old woman with fatigue, pruritus, jaundice, elevated bilirubin and alkaline phosphatase levels, and dilated intrahepatic bile ducts is Primary Biliary Cirrhosis (PBC). PBC is an autoimmune liver disease that primarily affects middle-aged women, leading to bile duct destruction and liver damage. The elevated alkaline phosphatase levels and presence of pruritus are typical in PBC due to impaired bile flow. Imaging showing dilated intrahepatic bile ducts supports the diagnosis of PBC as it indicates bile duct damage. Summary of other choices: B: Primary sclerosing cholangitis typically presents with strictures and beading of bile ducts on imaging. C: Gallstones would typically present with a common bile duct obstruction and not dilated intrahepatic bile ducts. D: Pancreatic cancer would typically present with different imaging findings and symptoms such as

Correct Answer: B

Rationale: The most likely diagnosis is Celiac disease (Choice B) due to the patient's symptoms of abdominal pain, bloating, diarrhea, and improvement with fasting, which are consistent with malabsorption seen in Celiac disease. The history of iron deficiency anemia also supports this, as it is a common complication of Celiac disease due to impaired absorption of nutrients. Irritable bowel syndrome (Choice A) typically does not improve with fasting, lactose intolerance (Choice C) does not usually cause iron deficiency anemia, and Crohn's disease (Choice D) typically presents with more severe symptoms and different patterns of improvement.