A 42-year-old woman presents with sweating and palpitations. She has a blood pressure of 140/90 mmHg and her pulse is 78 beats per minute. Physical examination reveals a 3.5-cm nonmobile, hard, nontender thyroid nodule. The physician decides to perform a RAIU scan.
Which of the following features is not associated with an increased risk of malignancy?
Hot nodule on RAIU. Thyroid nodules are fairly common with a 5% to 10% prevalence. Approximately 5% of thyroid nodules are malignant. (A, B, C) Factors associated with malignancy include history of radiation to the neck, male sex, hard and immobile mass, age greater than 70 years, worrisome ultrasound findings such as irregular borders and microcalcifications, cervical lymphadenopathy, and cold nodule on RAIU. Cold nodules are nonfunctional and do not absorb the radioiodine. Hot nodules, on the other hand, are autonomous (toxic) and readily absorb the radioiodine. However, hot nodules are benign and not associated with malignancy.
A 53-year-old man presents with diffuse joint pain, headache, macroglossia, and reports that his jaw looks larger now than it did in previous photos. Physical examination reveals acanthosis nigricans and numerous skin tags in the axillary and groin regions. The patient has an enlarged jaw and is noted to have a hoarse voice.
Which of the following is the next best step in management?
Insulin-like growth factor 1 (IGF-1) level. The patient in this question likely has acromegaly, a pituitary abnormality in which there is increased secretion of GH. GH circulates and stimulates production of IGF-1, an endocrine hormone produced primarily by the liver. In acromegaly, IGF-1 level is the best initial diagnostic study to perform. (A) GH levels fluctuate due to pulsatile secretion, so there is no utility in ordering GH levels for diagnostic purposes. However, some practitioners use an oral glucose tolerance test in which GH is not suppressed to <1 ng/mL by 2 hours. (C) Pituitary MRI would be the next best step after confirming the diagnosis of acromegaly with an increased IGF-1 in order to evaluate for the presence of a tumor. (D) Colonoscopy has no diagnostic merit in acromegaly. However, patients with acromegaly are at risk for colonic polyps and an increased risk for colon cancer.
A 62-year-old man with a history of congestive heart failure (CHF) presents with confusion, nausea, and vomiting. Physical examination reveals peripheral edema, bibasilar crackles, and jugular venous distention. The patient is found to have a sodium level of 112 mEq/L. The physician places the patient on free water restriction.
Which of the following laboratory values do you expect with respect to the fractional excretion of sodium (FENa) and urine sodium (UNa) with this condition?
FENa <1% and UNa <10 mEq/L. The patient in this question is hypervolemic (peripheral edema, bibasilar crackles, and jugular venous distention). Furthermore, he is severely hyponatremic (Na 112 mEq/L). The differential of hypervolemic hyponatremia includes CHF, cirrhosis, nephrotic syndrome, and advanced renal failure. The patient’s hypervolemic hyponatremia is likely secondary to his underlying CHF. Given that in CHF there is decreased effective arterial volume (EAV) from the decreased cardiac output, the kidneys compensate by absorbing more sodium. Thus, we expect urine sodium (UNa) to be low (<10 mEq/L) because it is mostly absorbed into the blood in response to diminished EAV. With similar reasoning, FENa will be low as well (<1%). (B) In advanced renal failure, there is decreased kidney function and thus sodium is not able to be reabsorbed; FENa and UNa will be higher than normal (>1% and >20 mEq/L, respectively) since sodium is predominantly being excreted.
A 24-year-old woman presents with labored breathing and abdominal pain. She endorses polydipsia and polyuria. She has a blood pressure of 130/90 mmHg, her pulse is 120 beats per minute, and her respiratory rate is 24 breaths per minute. Laboratory results reveal the following:
She is treated with intravenous insulin and isotonic saline solution. Two hours later her serum glucose concentration is 410 mg/dL with ample urine output.
Which of the following is the most appropriate next step?
Add potassium to the IV solution. The patient in this question is presenting in DKA. DKA is characterized by an elevated glucose (400 to 800 mg/dL) in the setting of abdominal pain, nausea/vomiting, Kussmaul respirations, “fruity” breath, dehydration, polydipsia, polyuria, polyphagia, and altered mental status. Since this causes an anion gap metabolic acidosis, patients often present with hypokalemia as well. The treatment is heavy IV fluids and IV insulin. Since insulin causes an intracellular shift of potassium, potassium should be added to the replacement solution (10 to 20 mEq/L) once urine output is ample and the serum potassium is <6.0 mEq/L. (A) Glucose should only be added once blood glucose reaches 250 mg/dL. (C) Intermediate-acting insulin can be given instead of continuous IV insulin once the anion gap has been corrected and the patient can tolerate PO intake. (D) Hypotonic saline solution has no role in the treatment of DKA.
A 29-year-old woman presents for follow-up after a fine-needle aspiration biopsy of a thyroid nodule showed malignant cells.
Which of the following types of thyroid cancer is the most common?
Papillary. Papillary thyroid cancer is the most common type, and fortunately the least aggressive. It spreads via lymphatics and is histopathologically characterized by nuclear grooves, pseudoinclusions, and psammoma bodies. Papillary thyroid cancer has an excellent prognosis when compared to the other types. (A) Follicular thyroid cancer is known for its vascular/capsular invasion and hematogenous spread. Prognosis is fair. (C) Medullary thyroid cancer is seen in the MEN II syndromes and arises from parafollicular (C) cells. Calcitonin is the tumor marker and the cancer spreads via lymphatics. Medullary thyroid cancer is histopathologically characterized by amyloid and has a fair prognosis. (D) Anaplastic thyroid cancer has the poorest prognosis of the different types of thyroid cancer, is exceedingly rare/ malignant, and histopathologically is undifferentiated without any resemblance to thyroid tissue.
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