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  1. 1. MARCH QUIZ 3 CRITIQUE Question 1 A 7 year old male with a history of prolonged bleeding time for many years presents to the ED with a particularly difficult epistaxis to control. He has never had a work up. Testing done revealed the following: PT: normal PTT: 55 seconds (control 34 seconds) CBC normal Bleeding time prolonged Factor VII levels are normal Platelet aggregation in response to ristocetin (RIPA) is abnormal Which of the following is most likely? A. Von Willebrand disease B. Factor XIII deficiency C. Factor VII deficiency D. Bernard-Soulier syndrome E. Vitamin K deficiency Critique A Question 2 A 1-year-old girl presents for a health supervision visit. Her father underwent kidney transplantation for end-stage renal disease due to autosomal dominant polycystic kidney disease. The parents request assessment of the child's kidney function. Her serum creatinine measurement is normal for age. Of the following, the MOST correct statement about serum creatinine measurements in the pediatric patient is that A a serum creatinine value of 0.6 mg/dL (53.1 mcmol/L) is considered normal for a 1- year-old child B healthy preterm infants (<36 weeks' gestation) typically have lower serum creatinine values than term infants C males and females have similar serum creatinine values up to 17 years of age D newborns in the first few days after birth have lower serum creatinine concentrations than those seen in 2-month-old infants E serum creatinine values are related more closely to patient height than to patient age in children Critique E Kidney function is assessed best by measurement of the glomerular filtration rate (GFR). GFR typically is quantitated by measuring the plasma clearance of a particular marker (eg, creatinine) that is eliminated by the kidneys. An ideal marker is a substance that is filtered freely at the glomerulus, not reabsorbed or secreted, and biologically inert (ie, neither metabolized nor synthesized by the kidney). The serum creatinine is the most frequently used agent to assess GFR clinically. Creatinine is derived from metabolism of the skeletal muscle protein creatine. Its generation is essentially constant, but because creatinine concentrations correlate with muscle mass, the pediatric patient, who has ever- increasing muscle mass due to growth, has increasing steady-state serum creatinine values with advancing pediatric age. In general, males and females have equivalent creatinine values until early adolescence, when the increasing muscle mass of the male adolescent alters the "normal" creatinine values seen in this age group. Normal GFR is approximately 100 mL/min per 1.73 m2 in females and 125 mL/min per 1.73 m2
  2. 2. in males. The GFR in the pediatric patient increases throughout the first postnatal year before reaching adult values by approximately 18 months of age. Creatinine clearance is calculated with serum creatinine, urine creatinine, and 24-hour urine volume. Due to difficulties with 24-hour urine collection in children, the Schwartz formula was created to allow the clinician to calculate an estimated GFR (eGFR) using the length or height of the child corrected to standard units of mL/min per 1.73 m2 . This formula (eGFR=kL/SCr) allows the pediatrician to estimate the GFR in infants, children, and adolescents with only the child's length or height (L) and the serum creatinine. The k is a constant that varies, based on age and sex. The value for k up to 1 year of age is 0.45; the k value for children from 1 to 13 years of age is 0.55. Due to considerations of increased muscle mass in adolescent males, the k value for males 13 to 21 years of age is 0.7, but this value remains 0.55 for adolescent females. The 1-year-old child in the vignette has a serum creatinine that is stated to be normal for age. Because a 1-year-old is approximately 75 cm in length, for the eGFR to be normal at 100 mL/min per 1.73 m2 , the serum creatinine would be SCr=kL/eGFR or (0.45 x 75)/100 = 0.3 mg/dL (26.5 mcmol/L). It is well known that serum creatinine is elevated in the newborn period and represents the maternal value. The values can remain elevated until approximately 10 days of age, after which time the creatinine returns to infant values in the 0.2 to 0.4 mg/dL (17.7 to 35.4 mcmol/L) range. Finney and associates demonstrated higher creatinine values in preterm infants (both 24 to 28 weeks' and 29 to 36 weeks' gestation) compared with term infants. Question 3 The parents of a newborn in whom a congenital severe-profound hearing loss has been diagnosed are seeking guidance about how to promote their infant's language development. You recommend enrollment in an early intervention program and obtaining hearing aids when the infant is young. His parents have never been exposed to an individual who has a hearing loss. They ask your opinion on the best approach for him to learn language. Of the following, the MOST important factor in language development of an infant or young child who has hearing loss is the use of A a high amount of verbal/nonverbal (gestures) communication between parents and child B an oral-aural method emphasizing the teaching of speech and the use of a child's residual hearing C hand-cued speech (using combined speech and hand cues) D manually coded English between parents and child E the bilingual (ASL and English)-bicultural (hearing and deaf culture) approach Critique A Multiple factors contribute to a family's decisions regarding their child who has confirmed hearing loss. Language-based early intervention results in superior expressive and receptive communication abilities compared with those of children identified at later stages of development. Family involvement, including verbal and nonverbal (gestures) communication, has a more significant positive effect on language development than any specific type of intervention. Hand-cued speech (Feldman HM. Evaluation and management of language and speech disorders in preschool children. Pediatr Rev. 2005;26:131-141  Gravel JS, O'Gara J Communication options for children with hearing loss. Ment Retard Dev Disabil Res Rev. 2003;9:243-251 Question 4 A 15-year-old girl presents with left-sided flank pain. She denies trauma, fever, frequency, and urgency. Her
  3. 3. past medical history is negative for urinary tract infections. Her family history is positive for kidney failure in her father from polycystic kidney disease. On physical examination, the girl's temperature is 37°C, respiratory rate is 16 breaths/min, pulse is 78 beats/min, and blood pressure is 130/86 mm Hg. Her physical examination findings are normal. Of the following, the BEST study to assess the cause of pain in this patient is A computed tomography scan of the abdomen and pelvis B diuretic renal scan (mercaptoacetyltriglycine [MAG3] furosemide renal scan) C magnetic resonance imaging of the abdomen D radiography of the abdomen and posterior rib cage E ultrasonography of the abdomen Critique E The adolescent described in the vignette has flank pain and a clinical history inconsistent with pyelonephritis. Such a presentation might be suspicious for a renal stone, but her borderline hypertension and positive family history of renal failure from polycystic kidney disease (PKD) raise the possibility of autosomal-dominant PKD (ADPKD), a genetic renal disease that also could present with flank pain. ADPKD is caused by mutations to PKD1 (chromosome 16, encodes for polycystin 1 and comprises 85% of cases) or PKD2 (chromosome 4, encodes for polycystin 2 and comprises 15% of cases). Individuals afflicted with ADPKD develop renal and extrarenal cysts, which can be seen best with renal ultrasonography (Item C190). The diagnostic criteria for ADPKD in patients younger than age 30 is more than one cyst in either kidney or the presence of one cyst in both kidneys. Only a few renal cysts may be present up to 30 years of age in affected individuals, but by age 50, hundreds to thousands of cysts may be present. Other imaging modalities to consider when evaluating a patient "at-risk" for ADPKD are computed tomography (CT) scan or magnetic resonance imaging (MRI). The CT scan has two major drawbacks: radiation exposure and exposure to radiocontrast with its potential nephrotoxic effects. Although MRI is not associated with the same risks as CT scan, this imaging modality is more costly and less well studied in ADPKD. Unless the child has renal insufficiency, using the intravenous MRI contrast agent gadolinium should be safe and allow excellent resolution. A MAG3 furosemide renal scan is a nuclear medicine test used to diagnose obstruction, usually in the setting of hydronephrosis. This test has no role in the diagnosis of ADPKD. Plain films may be helpful in looking for a rib fracture, but this is unlikely in the absence of trauma. Question 5 You are seeing a 30-year-old multigravid woman for prenatal counseling. She has had immune thrombocytopenic purpura for the past 5 years, and her spleen was removed 2 years ago. She asks you about the effects that her disease might have on her unborn child. Of the following, you are MOST likely to tell her that A if her newborn has thrombocytopenia, he or she will be treated with intravenous immunoglobulin B maternal platelet counts predict fetal risks of intracranial hemorrhage C maternal platelet transfusion during pregnancy will minimize the risk for neonatal thrombocytopenia D operative delivery of the newborn will reduce the risk of intracranial hemorrhage E the newborn will require a platelet transfusion soon after birth
  4. 4. Critique A The fact that the mother described in the vignette has immune thrombocytopenia is noteworthy. Because this condition is associated with immunoglobulin G (IgG) directed against maternal platelet antigens, transplacental acquisition of these antibodies by the fetus may occur after 30 weeks' gestation. As such, maternal-fetal surveillance is recommended, but no direct correlation exists between maternal platelet counts and fetal platelet counts or the risk of intracranial hemorrhage. Maternal platelet transfusion during pregnancy may help avoid concerns for the mother, but not the fetus or newborn. Although the risk for intracranial hemorrhage is only about 5% overall, it is greatest when fetal platelet counts are less than 20.0x103 /mcL (20.0x109 /L) because spontaneous intracranial hemorrhage may occur. An operative delivery of the newborn does not reduce the risk of intracranial hemorrhage significantly. Treatment of the newborn generally is supportive, with attention to the risk of thrombocytopenia significant enough to warrant platelet transfusion. Ninety percent of affected newborns require no treatment. However, platelet transfusion may be in order for any infant of a mother who has immune thrombocytopenic purpura when the neonate exhibits bleeding or has a platelet count of less than 20.0x103 /mcL (20.0x109 /L). The best treatment for affected infants is intravenous immunoglobulin (IVIg), which blocks circulating maternal IgG directed against platelet antigens and allows the newborn's platelet counts to rise. Platelet transfusion for the newborn is less effective than IVIg and may risk exposure to platelet-associated antigens that could induce a postnatal immune thrombocytopenia.