A 67-year-old woman with a history of GERD and congestive heart failure presents for her annual physical examination. Even though she has had no fractures, you recommend a DEXA scan to screen for osteoporosis.
What is the standard deviation threshold for beginning bisphosphonate therapy to treat osteoporosis?
T-score <−2.5. Treatment with bisphosphonates (such as alendronate) is typically started if the T-score is −2.5 standard deviations below the mean. T-score is defined as the bone mineral density (BMD) at the site when compared to the young normal reference mean (healthy 30-year-old). This is in contrast to Z-score, which compares to the age-matched normal. If the T-score is between −1 and −2.5, the diagnosis is osteopenia. If the T-score is below −2.5, then osteoporosis is diagnosed and a bisphosphonate should be started. Z-scores are typically used only when severe osteoporosis is suspected. Z-scores are also used in premenopausal women and in children.
A 42-year-old female nurse presents with confusion, dizziness, shakiness, and insatiable hunger. She denies any past medical history and reports that these symptoms have persisted for the last 2 months. Orange juice makes her feel better. She has a temperature of 37.2°C, blood pressure of 120/78 mmHg, heart rate of 92 beats per minute, respiratory rate of 14 breaths per minute, and oxygen saturation of 98% on room air. Laboratory results reveal the following:
Which of the following is the most likely diagnosis?
Insulinoma. The patient in this question is presenting with clinical symptoms and laboratory findings consistent with an insulinoma, a pancreatic β-cell tumor that secretes excessive insulin. (A) This question presents a nurse, which many students automatically associate with surreptitious injection of insulin in a hypoglycemic patient. However, this patient presents with an elevated C-peptide level, which is consistent with an endogenous source of insulin since pancreatic β-cells produce proinsulin (which breaks down into insulin and C-peptide). Therefore, insulinoma is likely the diagnosis since there are increased levels of both insulin and C-peptide in this patient. Note that surreptitious sulfonylurea use will also produce elevated insulin and C-peptide levels since this drug essentially stimulates proinsulin secretion. That is why it is critical to order a urine sulfonylurea level, which is undetectable in this patient. (C, D) Somatization disorder and glucagonoma do not produce hypoglycemia.
A 28-year-old man presents with severe watery diarrhea for the past 6 months. He also endorses “feeling flushed” and several episodes of wheezing. He has an insignificant past medical history. Vital signs are within normal limits and the patient is afebrile. Physical examination reveals a 3/6 holosystolic murmur at the left lower sternal border.
What is the next best step in management of this patient?
Urine 5-hydroxyindoleacetic acid (5-HIAA) level. The patient in this question is presenting with signs and symptoms of carcinoid syndrome. This is an uncommon syndrome caused by carcinoid tumors derived from neuroendocrine cells of the GI tract. The tumor secretes high levels of serotonin (5-HT). 5-HIAA is a breakdown product of 5-HT and thus will be elevated in this syndrome. Of note, symptoms of this syndrome (diarrhea, flushing, wheezing, and right-sided valvular disease) are not seen if the carcinoid tumor is limited to the GI tract (most commonly in the appendix). This is because 5-HT undergoes a first-pass metabolism in the liver. Carcinoid syndrome is also sometimes associated with niacin deficiency since tryptophan is used in the synthesis of niacin and in carcinoid syndrome there is increased tryptophan metabolism into serotonin. Niacin deficiency is associated with “the 3Ds”: depression, diarrhea, and dermatitis (pellagra). Treatment of carcinoid syndrome is with octreotide. (A, B) If this was a purely chronic diarrhea, stool culture might be warranted. However, supporting symptoms here establish carcinoid syndrome as the diagnosis. (C) Plasma catecholamine levels are increased in pheochromocytoma.
A 32-year-old man with no significant past medical history presents for follow-up of recently diagnosed hypertension. One month ago he fractured his tibia in a motorcycle accident and was found to have a blood pressure of 156/92 mmHg in the Emergency Department. Throughout his inpatient stay, his blood pressure remained elevated with systolic blood pressure readings consistently in the 150s. Workup was unremarkable and he was given low-dose hydrochlorothiazide to take once per day. Today his blood pressure is 148/88 mmHg and physical examination is unremarkable. Laboratory results reveal the following:
Plasma aldosterone concentration to plasma renin activity ratio. This patient is quite young and healthy to have a diagnosis of hypertension and should raise suspicion for a secondary cause of hypertension. The patient has not improved significantly on hydrochlorothiazide and given the presence of hypokalemia in the setting of high blood pressure, he likely has primary hyperaldosteronism. The screening test of choice is early morning plasma aldosterone concentration (PAC) to plasma renin activity (PRA) ratio. In primary hyperaldosteronism, we expect aldosterone to be high and renin to be low (from the increased kidney perception of high intravascular volume), so the PAC/PRA ratio should be greater than 20.
(A) Thiazide diuretics can indeed cause hypokalemia, but this patient is taking a low dose once per day and his degree of hypokalemia cannot solely be due to a thiazide diuretic. Furthermore, this patient is slightly hypernatremic, which further lends credence to the diagnosis of primary hyperaldosteronism. (C) CT angiography of the abdomen is warranted in screening for secondary hypertension caused by renal artery stenosis or fibromuscular dysplasia. However, these are causes of secondary hyperaldosteronism and the PAC/PRA ratio will be less than 10 in these patients. Secondary hyperaldosteronism could indeed be the diagnosis, but the first step in management is still to obtain PAC and PRA levels before pursuing such a modality. (D) Plasma catecholamine levels are increased in pheochromocytoma.
A 51-year-old woman with a history of type 2 diabetes mellitus presents with nausea, vomiting, and bloating. She reports not being able to finish her meals like she used to since she “gets full easily.” She has needed insulin for diabetic control for the last 9 years. Her home monitor blood glucose readings have been in the high 200s and low 300s for the last 2 weeks. Physical examination is significant for an obese woman with decreased sensation to pinprick and soft touch bilaterally in her lower extremities.
Which of the following is a therapeutic option for this patient’s condition?
Erythromycin. The patient in this question has diabetic gastroparesis, otherwise known as delayed gastric emptying. This is caused by diabetic autonomic neuropathy of the gastrointestinal tract. This is a common condition in patients with longstanding diabetes and manifests as anorexia, nausea, vomiting, and early satiety. Treatment of diabetic gastroparesis is multifactorial and involves increasing dietary fiber, changing the diet to include small, numerous meals, and using a prokinetic medication to help in gastric emptying. Both metoclopramide and erythromycin have prokinetic and antiemetic properties. Erythromycin is commonly used in an intravenous form for acute gastroparesis. (A) The patient is not presenting with symptoms suggestive of peptic ulcer disease and H. pylori triple therapy is not indicated without proper testing. (B, D) Omeprazole, a proton pump inhibitor, and ranitidine, a histamine H2 antagonist, are helpful as first-line treatments in the treatment of GERD, but are not useful in patients with gastroparesis.
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