Question 1.
A 28 year-old man comes to the emergency department for a head injury. He was recently diagnosed with HIV infection, and hit his head on a 3 meter diving board 2 hours ago. He is found to have a concussion which is treated appropriately. The next day, a group of divers and swimmers come to you concerned that they were exposed to the virus, and they want you to give them post-exposure prophylaxis. Which of the following is the most appropriate response?
All the swimmers should schedule RNA testing for this week
RNA testing will accurately detect the presence of the virus in as few as 9 days after exposure. This is faster than antibody tests, which have a 1-3 month window, but it is more expensive. Both tests are unnecessary given the extreme unlikelihood of exposure.
Anyone that swam in the pool within 72 hours should come for PEP prescriptions.
PEP is shown to be effective up to 72 hours prior to exposure. However, swimming in a pool with someone who has HIV is not an indication for PEP
PEP is unnecessary as HIV does not spread through air or pool water
Major takeaway
Post-exposure prophylaxis for HIV should be initiated within 72 hours of exposure through sexual intercourse or potentially-infected needle exposure. The virus cannot be spread through air or pool water.
Main explanation
HIV is not spread through pool water. The virus is killed by chlorine in the swimming pool and is extremely unstable in open air. The majority of HIV infections are contracted from sexual intercourse; this is followed by IV drug abuse, mother-to-child transmission, needle sticks, and blood transfusions. These concerned swimmers do not need PEP.
Current CDC guidelines for PEP include:
1. Healthcare workers who are exposed to blood or bodily fluids of a known or high risk HIVpatient via needle stick or non-intact skin,
2. Single event exposure in cases of unprotected sex, assault or needle-sharing.
Olympic diver Greg Louganis was diagnosed with HIV in 1988. That same year, at the 1988 Seoul Olympics, he suffered a concussion but went on to win the gold medal.
PEP is unnecessary because the patient, with early infection, has a low viral load
A recent diagnosis does not necessarily mean he was recently infected. Furthermore, viral load is actually highest early in infection before the body has time to develop antibodies to the virus.
PEP would be ineffectual because too much time has passed
PEP is most effective when treatment is initiated within an hour of exposure. However, effectiveness does not begin to significantly decline until after 72 hours post-exposure.
Question 2.
A 58-year-old woman comes to the emergency room because of of hip pain, fatigue, and nausea. Physical examination shows joint swelling and tenderness in multiple metacarpal and inter-phalangeal joints, and an X-ray shows diffuse osteoporosis and selective cortical bone loss. A metabolic panel also shows a markedly elevated serum calcium level and ultrasound reveals an abnormally large parathyroid gland on the patient’s right side. Which of the following laboratory values would also be expected in this case?
Decreased serum calcitriol
Calcitriol is the active form of vitamin D and is produced in the proximal tubules of the kidney by the action of 25-hydroxyvitamin D3 1-α-hydroxylase. Since this reaction is stimulated by parathyroid hormone, calcitriol levels would likely be elevated in this patient.
Hyperglycemia
Hyperglycemia, or elevated blood glucose levels, is most commonly seen in diabetes mellitus, diseases of the pancreas, and endocrine dysfunctions affecting the thyroid, adrenal, or pituitary glands. Increases in parathyroid function would not lead to hyperglycemia.
Hypochloremia
Hypochloremia, or abnormally low chloride levels in the blood, is most commonly associated with hypoventilation, chronic respiratory acidosis, vomiting, hyponatremia, elevated bicarbonate concentration, or cystic fibrosis. It would not be caused by overactive parathyroid glands.
Phosphaturia
Major takeaway
Primary hyperparathyroidism refers to an excess in parathyroid hormone due to overactive parathyroid glands. It is classically associated with elevated serum calcium and decreased serum phosphate levels.
Main explanation
This patient has primary hyperparathyroidism, an excess of parathyroid hormone caused by overactivity of the parathyroid glands. This increase in parathyroid hormone often leads to hypercalcemia due to its effects on the bones and kidney. In the bones, parathyroid hormonestimulates osteoclasts to increase bone resorption, while in the kidneys, it activates vitamin D, which then increases calcium resorption in the digestive tract.
In the kidneys, parathyroid hormone also acts to reduce the reabsorption of phosphate from the proximal tubules, leading to an increase in the excretion of phosphate in the urine. In the serum, however, phosphate levels are still normal in approximately 50% of patients due to the effects of parathyroid hormone on the uptake of phosphate from the intestine and bones into the blood.
Proteinuria
Proteinuria, or excess protein levels in the urine, is most commonly caused by kidney problems involving filtration or reabsorption of proteins from the serum. It would not likely be caused by an increase in parathyroid function.
Question 3.
A 20-month-old boy comes to the emergency department because of rectal bleeding and abdominal pain. The mother says that 3 days ago, he first had a small episode of rectal bleeding but that he did not show any signs of irritation or pain and that he was acting normal throughout the day. However, today he was found gripping his abdomen and crying in pain. Abdominal examinationshows generalized tenderness to palpation. An abdominal X-ray shows a gasless abdomen and mild intestinal dilatation. Which of the following condition does the patient most likely have?
Duodenal atresia
Infants with duodenal atresia typically have gastric distension and bilious vomiting. Approximately 25% of newborns with duodenal atresia have Down syndrome.
Gastroschisis
Gastroschisis and omphaloceles are often confused, but gastroschisis does not involve the umbilical cord, is not enclosed in a membranous sac, and is almost always to the right of the umbilicus.
Meckel diverticulum
Major takeaway
Rule of twos applies to Meckel diverticulum, which occurs in about 2% of the population, is about 2 in long, is found about 2 ft from the ileocecal valve, 2% of patients develop a complication over their lifetime, and has a male to female ratio of 2:1. Complications can include a volvulus or malrotation.
Main explanation
This patient likely has a lower GI bleed from a Meckel diverticulum. Meckel diverticulum is the most common congenital anomaly of the gastrointestinal tract. Gastrointestinal bleeding from a Meckel diverticulum is caused by an ulceration of the small bowel secondary to acid secreted by the ectopic gastric mucosa in the diverticulum. The bleeding is often painless. The classic description you should remember is the rule of twos: Meckel diverticulum occurs in about 2% of the population, is about 2 in long, is found about 2 ft from the ileocecal valve, approximately 2% of patients develop a complication over their lifetime, and the male to female ratio is 2:1.
This boy has developed a complication from his Meckel diverticulum, a volvulus. Although the plain radiograph of the abdomen only shows a gasless abdomen and mild intestinal dilation, patients with volvulus can even have a completely normal X-ray; therefore plain radiographsare not used to confirm the presence of a malrotation or volvulus.
Omphalocele
An omphalocele is a type of abdominal wall defect that occurs when the abdominal viscera herniates through the umbilicus into a sac covered by peritoneal tissue and amniotic membrane.
Tracheoesophageal fistula
This involves the upper airway and should not have been considered given the clinical picture shown above. A tracheoesophageal fistula typically occurs with esophageal atresia and many cases are not detected prenatally.
Question 4.
A 45-year-old woman comes to the office because of shortness of breath and chest tightness on exertion, which she noticed for the past two months. Examination shows mildly jaundiced conjunctivae, several spider nevi on her upper torso, and a barrel chested appearance. She was diagnosed with asthma a month ago, but says that asthma medication has not improved her breathing. She does not smoke and works as a hotel manager. A chest X-ray is obtained. Which of the following is the most likely diagnosis?
Alpha 1-antitrypsin deficiency
Major takeaway
Patients with emphysema without risk factors or recurrent spontaneous pneumothorax(caused by the rupture of bullae) should be investigated for alpha 1-antitrypsin.
Main explanation
This X-ray shows increased antero-posterior diameter (which translates radiographically to uniform increase in radiolucency of both lung fields) and flattening of hemidiaphragms, which is consistent with emphysema (COPD). Emphysema in a young patient with no risk factors should raise the question of alpha 1-antitrypsin deficiency, especially in the presence of cirrhosis (suggested by spider nevi and jaundice in this case), pancreatitis, gallstones, bronchiectasis, or recurring spontaneous pneumothorax.
Bilateral pneumothorax
Bilateral pneumothorax is a rare condition that occurs mainly in patients with so-called buffalo chest, where the anatomical separation of the left and right pleural spaces is absent; thus, air trapped in one pleural space can move from to the other side, causing bilateral pneumothorax.
Kartagener syndrome
Patients with primary ciliary dyskinesia (Kartagener syndrome) have situs inversus, which is not seen in this patient, along with bronchiectasis and infertility.
Pneumomediastinum
Pneumomediastinum is characterized by an increase in radiolucency on both sides of the heart border and the emerging large arteries.
Pulmonary hypertension
Pulmonary hypertension is a long-term complication of chronic obstructive pulmonary disease, characterised radiographically by prominent pulmonary trunk and pulmonary arteries, which in time leads to cor pulmonale, with right ventricular hypertrophy and subsequent heart failure.
Question 5.
A 39-year-old woman, gravida 4, para 3, comes to the office for an evaluation at 20 weeks’ gestation. Given her advanced maternal age, she is concerned about having a child with a chromosomal abnormality. Which of the following results on the quadruple screening test are most likely to raise suspicion of Down syndrome in the fetus?
Decreased α-fetoprotein, decreased estriol, decreased β-human chorionic gonadotropin
This quadruple screen profile is not associated with any particular chromosomal abnormality. β-human chorionic gonadotropin (βhCG) and inhibin A would be increased in a positive Down syndrome screen.
Decreased α-fetoprotein, decreased estriol, decreased β-human chorionic gonadotropin, increased
This quadruple screen profile is not associated with any particular chromosomal abnormality. α-fetoprotein and estriol would be decreased in a positive Down syndrome screen, and β-human chorionic gonadotropin (βhCG) would be increased.
Decreased α-fetoprotein, decreased estriol, decreased β-human chorionic gonadotropin, unchanged
This quadruple screen profile is associated with trisomy 18, also known as Edwards syndrome. Edwards syndrome results in profound structural organ defects in many systems and developmental delay. Of note, inhibin A can either be unchanged or decreased.
Decreased α-fetoprotein, decreased estriol, increased β-human chorionic gonadotropin, increased inhibin A
Major takeaway
The quadruple test is used to screen for Down syndrome during the second trimester. Decreased α-fetoprotein, decreased estriol, increased β-human chorionic gonadotropin (βhCG), and increased inhibin A are associated with a positive screening result for Down syndrome.
Main explanation
Quadruple screening consists of analyzing the maternal serum marker pattern for:
1) α-fetoprotein
2) estriol,
3) β-human chorionic gonadotropin (βhCG)
4) inhibin A.
This test is routinely conducted on pregnant women between 15-22 weeks pregnant (second trimester) to screen for chromosomal abnormalities, including trisomy 21 (Down syndrome) and trisomy 18. The following quad screen profiles are associated with particular chromosomal abnormalities.
Trisomy 21: Decreased αFP, decreased estriol, increased ß hCG, increased inhibin A
**Remember 2 up and 2 down in 21
Trisomy 18: Decreased AFP, decreased estriol, decreased B-hCG, decreased inhibin A
**Remember You are UNDERage at 18, so all levels are decreased
Lauren Potter is an American actress with Down Syndrome who is best known for her role as Becky Johnson on the ABC hit show Glee. She was recently appointed to the President’s Committee for People with Intellectual Disabilities, where she will advise the White House regarding issues in this population.
Increased alpha-fetoprotein, increased estriol, increased β-human chorionic gonadotropin, increased inhibin A
This quadruple screen profile is not associated with any particular chromosomal abnormality. α-fetoprotein and estriol would be decreased in a positive Down syndrome screen.
Question 6.
A 30-year-old woman, gravida 2, para 2, comes to the office because of rapidly changing moods, irritability, anxiety and tearfulness for 3 days. Her second daughter was born by spontaneous vaginal birth a week ago. Today, she cried whilst breastfeeding, her husband was very concerned. She has not been sleeping very well, and feels very exhausted. She says that she was emotional after her first pregnancy, but that resolved two weeks post-delivery. There is no history of depression, or other medical problems. She has still been able to take care of her children, even though she has been labile in her moods. Which of the following is the most likely diagnosis?
Childbirth-related post traumatic stress disorder
Childbirth-related post traumatic stress disorder is a well-described subset of posttraumatic stress disorder (PTSD). Patients may experience intrusive symptoms such as flashbacks and nightmares, as well as symptoms of avoidance, problems in developing a mother-child attachment, not having sex in order to prevent another pregnancy, and avoidance of birth and pregnancy related issues.
Normal postpartum mood
This patient has symptoms of postpartum blues, which is common and occurs in up to 85% of women. It is characterized by affective instability with rapidly changing moods, tearfulness, irritability and anxiety.
Postpartum blues
Major takeaway
Postpartum blues is common with symptom onset several days after delivery and lasting up to 2 weeks. Typical symptoms include; mood lability, irritability, appetite changes and sleep disturbance. Postpartum depression is similar to postpartum blues, however symptoms are more persistent and cause functional impairment.
Main explanation
Postpartum blues is common and occurs in up to 85% of women. Women experience affective instability with rapidly changing moods, tearfulness, irritability and anxiety. Symptoms usually peak 4-5 days after delivery and last several days. Symptoms are generally self-limiting and resolve spontaneously within 2 weeks of giving birth. Postpartum blues does not interfere with the mother’s ability to function and care for her child. No treatment is required, but the patient will benefit from improved sleep and social support.
Women with postpartum blues can later go on to develop postpartum depression (PPD). This condition is characterized by changes in sleep, energy level, appetite, weight, and concentration. Additionally, mothers with PPD may feel overwhelmed and unable to care for the baby, or feel that they are not bonding with their baby.
Postpartum depression
Postpartum depression (PPD) affects approximately 10% of women and the symptoms are more severe than in postpartum blues. A history of depression either prior to, or during pregnancy is the primary risk factor. PPD is characterized by changes in sleep, energy level, appetite, weight, and concentration.
Postpartum psychosis
Postpartum psychosis is characterized by onset within two weeks of childbirth of a combination of psychotic symptoms (e.g. hallucinations and delusions) and symptoms of a mood disorder. Women with postpartum psychosis are at increased risk of harming their baby. Hospitalization may be appropriate and be considered on a case-by-case basis.
Question 7.
A 54-year-old woman comes to the clinic because of long-term fatigue, nausea, and continuous craving of salty foods. She has had several occasions of fainting after standing quickly. Her temperature is 37°C (98.6°F), pulse is 110/min, respirations are 20/minute, and blood pressure is 80/50 mm Hg. Physical examination shows increased pigmentation of the skin on her elbows and oral mucosa. She has a family history significant for myasthenia gravis. Laboratory studies show:
Which of the following is the most likely diagnosis?
Cushing disease
Cushing disease is caused by an ACTH-secreting pituitary adenoma, which increases serum cortisol levels in the blood, leading signs and symptoms of hypertension, weight gain, moon facies, and hyperglycemia. Although this patient has high ACTH levels, she has low cortisol levels, hypoglycemia, and hypotension.
Primary adrenal insufficiency due to Addison disease
Major takeaway
Addison disease, a chronic form of primary adrenal insufficiency, results from destruction of the adrenal cortex. Decreased aldosterone secretion results in hypotension, hyponatremia, and hyperkalemia and disinhibits secretion of CRH, MSH, and ACTH. Decreased cortisol causes hypoglycemia, fatigue and compromised response to stress.
Main explanation
Addison disease is caused by adrenal cortical atrophy or destruction. There are multiple causes for this destruction such as infection, metastatic neoplasms, and autoimmune destruction. In the developing world, tuberculosis is a common cause. In the developed world, the most common cause is autoimmune destruction. Addison disease is associated with HLA subtypeB8, a characteristic shared with myasthenia gravis, another autoimmune condition that results in antibodies directed against the postsynaptic nicotinic acetylcholine receptors at the neuromuscular junction.
In Addison disease, destruction of the adrenal cortex results in low levels of serum cortisol and aldosterone. Since serum aldosterone is low, patients tend to present with hypotension, hyponatremia, and hyperkalemia. Since serum cortisol is low, negative feedback on the pituitary and hypothalamus diminishes and ACTH will be elevated accordingly. Sometimes patients will present with hypoglycemia because of insufficient cortisol to counteract insulinand initiate gluconeogenesis. Hyperpigmentation of the skin and mucosa is a result of an increase in melanocyte-stimulating hormone (MSH). a by-product of ACTH production from pro-opiomelanocortin (POMC). In addition, cortisol is a stress hormone that potentiates the body’s ability to respond to changes in the environment. Without adequate cortisol, weakness, fatigue and weight loss will set in.
Primary adrenal insufficiency due to Waterhouse-Friderichsen syndrome
In Waterhouse-Friderichsen syndrome, primary adrenal insufficiency occurs due to hemorrhage into the adrenal gland via disseminated intravascular coagulation (DIC). Patients often have progressive hypotension, which leads to shock. This patient’s condition has been occurring long-term, and she does not have a fever.
Secondary adrenal insufficiency
Secondary adrenal insufficiency is not caused by pathology to the adrenal cortex, but to the pituitary gland, resulting in decreased ACTH production and therefore decreased cortisol secretion. This patient, on the contrary, has elevated ACTH. Also, hyperkalemiausually does not occur in secondary adrenal insufficiency because aldosterone synthesis is preserved.
Tertiary adrenal insufficiency
Tertiary adrenal insufficiency involves pathology to the hypothalamus, which results in diminished CRH production and therefore decreased ACTH production by the anterior pituitary, resulting in effects similar to secondary adrenal insufficiency and therefore not a likely diagnosis in this patient. Chronic exogenous (iatrogenic) steroid use is the usual culprit.
Question 8.
A 25 year old woman with a history of asthma complains of worsening asthma attacks. Before, she had symptoms less than twice a week with less than two night attacks a month. These symptoms were easily controlled with her albuterol inhaler. Now, she is symptomatic every day of the week with frequent weekly night attacks. The albuterol inhaler helps control the acute attack, but she is concerned that she needs additional medication. You decide to add low-dose inhaled steroids and a long-acting bronchodilator. Which of the following drugs would be the most appropriate long-acting bronchodilator to add?
Salmeterol
Main explanation
Salmeterol (choice A) and Theophylline (choice C) are the only two drugs listed that are considered long-acting bronchodilators. Salmeterol is a long-acting beta-2 agonist that acts as a bronchodilator by increasing cAMP in smooth muscle cells throughout the respiratory system resulting in muscle relaxation. Theophylline is a methylxanthine that also causes smooth muscle relaxation by increasing levels of cAMP. Between the two, salmeterol would be preferred because theophylline has a narrow therapeutic index with risk of cardiotoxicity and neurotoxicity; therefore choice E is incorrect. Cromolyn (choice B) prevents the release of mediators from mast cells and is therefore not a bronchodilator. Zafirlukast (choice D) is an antileukotriene that inhibits leukotriene receptors to mediate the inflammatory response and is therefore not a bronchodilator.
Salmeterol or Theophylline
9%
Question 9.
A 75-year-old man comes to the clinic because of difficulty passing urine, as well as increased urinary urgency and frequency. These symptoms have been getting progressively worse over the past 12 months and now he has times where he wets himself, causing much embarrassment and distress. Digital rectal examination shows a diffusely enlarged, regular prostate. An MRI is performed and a slice is shown below. Which of the following is one possible pharmacological treatment for this condition?
Spironolactone
Spironolactone is a potassium-sparing diuretic medication that is most commonly used in patients with cirrhosis or heart failure. It has no role in the management of Benign prostatic hyperplasia.
Sildenafil
Sildenafil, commonly known as Viagra, is a phosphodiesterase-5 (PDE5) inhibitor. This class of medication is used first line in the treatment of erectile dysfunction.
Metoprolol
Metoprolol is a cardioselective beta-1 receptor antagonist that reduces heart rate, cardiac output, and blood pressure. It is most commonly used in the treatment of myocardial infarction, heart failure, and hypertension.
Oxybutynin
Oxybutynin is an anticholinergic medication that is used first line for the treatment of of overactive bladder. This condition is characterised by urinary frequency, urgency, nocturia, and urge incontinence.
Doxazosin
Major takeaway
Benign prostatic hyperplasia is a common condition in elderly males that is a major cause of lower urinary tract obstruction symptoms. Alpha-blockers relax smooth muscle in the prostateand bladder neck and can alleviate the symptoms associated with BPH.
Main explanation
The signs, symptoms, and magnetic resonance image, showing an enlarged prostate without a focal mass, are in line with benign prostatic hyperplasia (BPH). The prostate increases in size with age and, as a result, BPH is common in elderly men. Due to the anatomical location of the prostate its overgrowth can compress the urethra causing obstructive lower urinary tractsymptoms such as poor urinary stream, hesitancy, dribbling, incomplete voiding, and overflow incontinence.
Treatment should be guided by symptoms which can be assessed using the International Prostate Symptom Score (IPSS).
Doxazosin is an alpha blocker. Alpha blockers are used first line in the pharmacological treatment of BPH. They relax smooth muscle in the prostate and the bladder neck, thus decreasing the blockage of urinary flow.
Question 10.
A 30-year-old male presents to the clinic for treatment on the advice of his girlfriend. He reports a history of extreme shyness and has been the “silent one” since childhood. He has very few friends and works as a computer technician. He does not hang out with his coworkers outside of work since he is afraid they will not like him. Which of the following is most likely associated with the patient’s condition?
The patient is likely to use splitting as a defense mechanism
This patient is not likely to use splitting as a defense mechanism. Patients with borderline personality disorder (a Cluster B personality disorder) will commonly use the defense mechanism of splitting. Spitting is defined as labeling people as all good or all bad.
This patient has a Cluster C personality disorder
Major takeaway
Avoidant personality disorder is a cluster C disorder where patients desire relationships with others. However, their fear of rejection causes them to avoid social settings.
Main explanation
This patient most likely has avoidant personality disorder. According to the DSM-V, avoidant personality disorder is characterized by a pervasive pattern of social inhibition, feelings of inadequacy and hypersensitive to negative evaluation. Patients are described as extremely shy, inhibited by new situations and fearful of disapproval and social rejection. These traits are seen in this clinical scenario. Avoidant personality disorder is a Cluster C personality disorder, characterized as anxious or fearful. A person with avoidance personality disorder desires relationships with others, unlike schizoid personality disorder in which a person prefers to be alone.
Avoidant personality disorder usually starts at a young age; however, it is not generally diagnosed until the patient is older than 18-years-old. The trait appears to be stable throughout adulthood. The social anxiety patients experience is thought to be due to dysfunction in the amygdala and its connections.
The patient is likely to have a first degree relative with schizophrenia
There is no genetic association between avoidance personality disorder and schizophrenia. However, in Cluster C personality disorders there is a genetic association with anxiety disorders. In addition, there is a genetic association between schizophrenia and Cluster A personality disorders, with the strongest correlation existing with schizotypal personality disorder.
This patient has a Cluster A personality disorder
This patient does not have a Cluster A personality disorder. Cluster A disorders are characterized as odd or eccentric. These include paranoid personality disorder, schizoid personality disorder, and schizotypal personality disorder.
This patient has a personality disorder not otherwise specified (NOS)
A diagnosis of personality disorder not otherwise specified is reserved for those patients who fail to meet the criteria for any of the defined personality disorders.
