confirm the cause of this patient’s amenorrhea? X
A.
Ur ine beta-h CG CG
!
B.
Foll Follic icle le stim stimul ulati ating n g horm hormone one (FS (FSH) H)
X
C.
Thyr Thyroi oid d stimu stimula lati ting ng horm hormon one e (TSH) (TSH)
X
D.
Karyotyping
X
E.
Prolactin
You did not answer this question. Explanations: A.
Measuring a urine beta-hCG (answer A) is always the first step in working up a case of primary or secondary amenorrhea. Before chasing down other possibilities, you should always rule out the possibility of pregnancy in any reproductive-aged woman.
B.
This patient patient presents presents with the classic classic signs, signs, symptoms, symptoms, and demograp demographics hics of menopause. menopause. If the the diagnosis diagnosis of menopause menopause is uncertain, uncertain, the finding finding of an elevated elevated FSH can confirm confirm the diagnosis diagnosis (answer B), although in a patient such as this one the clinical history and findings are likely to be sufficient. The other answer choices provide useful information, and can be part of the workup of primary or secondary amenorrhea. While most of them are reasonable tests to order, none are likely to confirm the diagnosis suggested by the question stem. Measuring a urine beta-hCG (answer A) is always the first step in working up a case of primary or secondary amenorrhea. Before chasing down other possibilities, you should always rule out the possibility of pregnancy in any reproductive-aged woman. Finding an elevated thyroid stimulating hormone (answer C) would confirm a diagnosis of hypothyroidism, which is a cause of secondary amenorrhea. It is true that some of the symptoms of menopause and hypothyroidism overlap, but the giveaway in the question stem was the patient’s description of having hot flashes. If you suspect that a patient has testicular feminization syndrome, karyotyping (answer D) can reveal a 46 XY genotype. These patients will present with primary amenorrhea – that is, a complete absence of menstrual periods. The primary defect in testicular feminization syndrome is the dysfunction or absence of the testosterone receptor, which leads to a phenotypical female with male chromosomes. Hyperprolactinemia (answer E) is another cause of secondary amenorrhea, which is why after a pregnancy test, the next step in a standard amenorrhea workup is the measurement of prolactin and TSH.
C.
Finding Finding an elevated elevated thyroid stimulat stimulating ing hormone hormone (answer (answer C) would confirm confirm a diagnosis diagnosis of hypothyroidis hypothyroidism, m, which is a cause cause of secondary secondary amenorrhea. amenorrhea. It is true that that some of the symptoms symptoms of menopause and hypothyroidism overlap, but the giveaway in the question stem was the patient’s description of having hot flashes.
D.
If you suspect suspect that a patient patient has testicular testicular feminizati feminization on syndrome, syndrome, karyotyping karyotyping (answer (answer D) can reveal reveal a 46 XY genotype. genotype. These patients patients will will present with with primary amenorrhe amenorrhea a – that is, a complete complete absence of menstrual periods. The primary defect in testicular feminization syndrome is the dysfunction or absence of the testosterone receptor, which leads to a phenotypical female with male chromosomes.
E.
Hyperprolact Hyperprolactinemi inemia a (answer E) is another another cause of secondary secondary amenorrhea amenorrhea,, which is why after after a pregnancy pregnancy test, the next step step in a standard amenorrhe amenorrhea a workup is the measurem measurement ent of prolactin prolactin and TSH.
This question is not currently linked to the learning objective database. Question problem? Question # 87 Select the single best answer to the numbered question.
A 10 year old male presents presents with a one week history of a limp that seems to be getting worse. worse. The patient describes hip and upper leg pain pain that is worst when he stands with his full weight on his left foot. The pain started last week, but yesterday it suddenly worsened after he jumped off of a moving swing yesterday. On physical examination, the patient moderately obese and at Tanner stage 2 of sexual development. He walks with a pronounced limp, and refuses to bear weight on the left foot. There is marked limitation of both active and passive range of motion at the hip. Examination of other joints is within normal limits. Which of the following is the most likely diagnosis in this patient? X
A.
Legg Legg-C -Cal alve ve-P -Per erth thes es disea disease se
!
B.
Slip Slippe ped d capi capital tal femor femoral al epi epiphy physi sis s
X
C.
Tr an an si si en en t s yn yn ov ov itit is is
X
D.
O sg sg oo oo dd- Sc Sc hl hl at at te te r d is is ea ea se se
X
E.
Growing pains
You did not answer this question. Explanations: A.
Legg-Calve-Perthes disease (choice A) is an idiopathic avascular necrosis of the hip that occurs in children ages 3-12 with a pea k incidence is 5-7 years old. It predominantly affects males and 10% of cases are familial. Patients present with a limp and Trendelenburg gait (pelvis tilts downward on unaffected side while trunk sways toward affected side during stance). Pain is mild and usually referred to anteromedial thigh or the knee, but can lead to disuse causing atrophy of the thigh and buttock. Physical exam reveals limited internal rotation and abduction of the hip. Initial radiographs are usually normal, but bone scans can show decreased perfusion to the femoral head, and MRI will show marrow changes.
B.
This is a fairly fairly classic classic presentation presentation of SCFE, SCFE, or slipped capital capital femoral femoral epiphysis epiphysis (answer (answer B). This This is a common cause cause of hip pain and altered altered gait in obese obese pre-adolescent pre-adolescents, s, and is caused caused by displacement of the capital femoral epiphysis from the femoral neck through the growth plate. A few extra teaching points ! 1) The plain film x-rays for this patient would show posterior displacement of the left femoral epiphysis. This finding is often described as “ice-cream slipping off a cone.” 2) It is important to recognize this diagnosis and treat it in a timely manner to prevent joint damage. Patients should be immediately referred to an orthopedic surgeon for the placement of a screw through the center o f the epiphysis. Acute slips are unstable, and require a hospital admission and bed rest. 3) As mentioned above, the typical patient is an obese child in early adolescence (
C.
Transient Transient synovitis synovitis (choice (choice C), or TS, TS, should be in the differenti differential al of a limp, especiall especially y in the pre-school pre-school to school-age school-age group, group, as it is a common disorder disorder that presents presents with with pain and limitatio limitation n of hip motions arising without a clear cause and resolving with only conservative therapy. Most kids present with symptoms for less than 1 week, are usually afebrile and non-toxic appearing. The cause is unknown, though an infectious cause is assumed because up to half of kids with TS had a recent upper respiratory tract infection. TS is managed with NSAIDs and rest for afebrile patients with a benign WBC and ESR. Imaging is needed if the clinical picture is concerning for hip infection.
D.
Osgood-Schla Osgood-Schlatter tter disease disease (choice (choice D) is an osteochondriti osteochondritis s of the tibial tuberosit tuberosity y caused by overuse overuse in active active individuals. individuals. (Sports (Sports such as basketbal basketballl and gymnastics gymnastics are common common culprits culprits since jumping puts a lot of stress on the tibial tuberosity.) It usually presents in a 13-14 year old boy or 11-12 year old girl who has recently undergone a growth spurt. The most common complaint is anterior knee pain that progressively worsens over time, and is improved with rest. The diagnosis is clinical and the treatment is conservative.
E.
Growing Growing pains (choice ce E) are recurrent recurrent self-limite self-limited d extremity extremity pain most most commonly commonly described described by kids ages 2-12 2-12 years old. They They are benign and and resolve on their their own. The cause cause of growing pains pains is unknown, and although they occur in growing children, they are not caused by growth itself. There are no radiographic findings for growing pains, so the diagnosis is one of exclusion.
This question is not currently linked to the learning objective database. Question problem? Question # 88 Select the single best answer to the numbered question.
A 38 year old woman has sudden onset of nausea and vomiting and severe, colicky flank pain that radiates radiates to the perineum. On physical examination, the patient shifts position frequently and seems unable to sit still. Urinalysis shows trace protein, 3+ blood, pH = 7.2. Microscopic analysis shows many red cells and a few white cells, but no casts or bacteria. Laboratory analysis shows: Na+ 141 K+ 3.0, Cl- 119, HCO3- 12, BUN 17, Creatinine 1.0, glucose 111, 111, calcium 9.8, magnesium 1.6, phosphate 3.0. Which of the following is the most likely etiology of this patient’s electrolyte abnormalities? X
A.
Increa Increased sed product production ion of endog endogenou enous s lacti lactic c acid acid
!
B.
Decreas Decreased ed net net secreti secretion on of H+ H+ at the the distal distal rena renall tubule tubule
X
C.
D ef ef ic ic ie ie nc nc y of of a ld ld os os te te ro ro ne ne
X
D.
Excess Excessive ive releas release e of para parathy thyroid roid hormon hormone e (PTH) (PTH)
X
E.
Phys Physio iolo logi gica call stres stress s respon response se to pai pain n
You did not answer this question. Explanations: A.
Increased production of lactic acid (answer A) causes lactic acidosis, which causes an increased anion gap metabolic acidosis. Common causes of lactic acidosis include circulatory failure, ischemia, and inborn errors of metabolism.
B.
Key teaching teaching point: point: the differential differential diagnosis diagnosis for for a NON-anion NON-anion gap metabolic metabolic acidosis acidosis is short – think think of RTAs RTAs and GI bicarbonate bicarbonate loss. loss. This question question describes bes a patient with with nephrolithias nephrolithiasis is who is subsequently found to have a non-anion gap metabolic acidosis. These findings are consistent with a type 1 renal tubular acidosis (RTA) in which there is impaired secretion of H+ into the distal tubule and collecting duct (answer B). This in turn leads to the decreased bicarbonate and metabolic acidosis, and the alkalinization of the urine causes nephrolithiasis. Other key findings that help you make the d iagnosis of a Type 1 or distal RTA are the low K+ and urine p H>5.5. This question raises a few important teaching points, as well. 1) Questions about RTAs are very common on the shelf exams – even the surgery shelf exam has been known to have a question about RTAs on it! You need to be able to diagnose them at a glance a nd distinguish amongst the three types based on lab data and urine pH. This latter task unfortunately requires some first-year med student style rote memorization, but here is a helpful chart to help you with that task: http://web.archive.org/web/20070808145429/http://www.mayoclinic.com/health/renal-tubular-acidosis/AN00642 2) Broadly speaking, there are three ways that a person can develop metabolic acidosis: 1) Increased H+ entering the body (from lactate or ketoacids, for example) 2) Inability of H+ to be excreted by the kidney (as in RTA) 3) Inappropriate loss of HCO3- in the GI tract or the kidney Situation #1 causes a metabolic acidosis with an increased anion gap, while situations #2 and #3 cause a non-anion gap metabolic acidosis. Remember that the anion gap is calculated as (Na+) – (Cl-) – (HCO3-), and should be less than or equal to 12 +/- 4. If the anion gap is elevated, you should begin working through the “MUDPILES” mnemonic to look for a cause. If the anion gap is NOT elevated but the patient has a metabolic acidosis, there are really only two common things to think about: renal tubular acidosis and GI loss of bicarbonate (caused by diarrhea or loss of GI fluid beyond the ligament of Treitz). Increased production of lactic acid (answer A) causes lactic acidosis, which causes an increased anion gap metabolic acidosis. Common causes of lactic acidosis include circulatory failure, ischemia, and inborn errors of metabolism. A deficiency of aldosterone (answer C) is the pathologic mechanism underlying Type IV RTA. This results in an inability to absorb sodium at the intercalated cells of the collecting duct, resulting in hyponatr emia, hyperkalemia, and impaired H+ secretion leading to a non-anion gap acidosis. Excessive release of parathyroid hormone (answer D) causes hyperparathyroidism. The characteristic abnormality
