Clin Lab - Pediatrics Flashcards

1
Q

What is an alkali denaturation test (Apt test) used for?

A

Differentiates maternal from newborn blood in blood fetal vomit/stool/aspiration

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2
Q

Does fetal Hgb denature in alkaline solutions?

A

NO

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3
Q

Does adult Hgb denature in alkaline solutions?

A

YES

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4
Q

Describe the make-up of adult hemoglobin (Hb A).

A

2 alpha & 2 beta chains

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5
Q

Describe the make-up of fetal hemoglobin (Hb A).

A

2 alpha & 2 gamma chains

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6
Q

Describe the alkali denaturation test (Apt test) process.

A
  • Sample is mixed w/ 1% NaOH & color assessed
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7
Q

alkali denaturation test (Apt test) (+) test for adult hgb color

A
  • yellow-brown color
  • think tea/coca cola
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8
Q

alkali denaturation test (Apt test) (+) test for fetal hgb color

A

color–>pink

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9
Q

NOTE on newborn screening test

A

All states require a set of screening tests to look for congenital d/o

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10
Q

Major types of congenital newborn screenings?

A
  1. Congenital heart dz
  2. Hearing test
  3. Genetic d/o
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11
Q

What are the types genetic disorders screened in newborns?

A
  • Errors of metabolism
  • Hormone disorders
  • Hemoglobinopathies
  • Immune deficiencies
  • other
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12
Q

Describe congenital heart dz screening.

A

Screens for critical congenital heart issues that cause hypoxemia & likely will need correction emergently or w/n 1st year of life

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13
Q

Examples of congenital heart dz?

A
  • Tetralogy of Fallot
  • Transposition of the great arteries
  • Correction of the aorta
  • Tricuspid or pulm atresia
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14
Q

When will hypoxemia likely become apparent?

A

O2 sats < 80%

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15
Q

What does the typical testing algorithm for congenital heart dz start with?

A

Test O2 sat using right hand & either foot

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16
Q

Why test the right hand & either foot?

A

Looking a perfusion (if coarctation we’re looking on above and below)

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17
Q

What is the timing go the newborn screenings?

A
  • Initial screen >/= 24hrs after birth
  • repeat screen at 1hr & 2hrs
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18
Q

Why is the initial new born screening measured >/= 24hrs after birth?

A

Babies can have normal transient hypoxemia

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19
Q

Positive screening test if any of the following are met:

A
  • O2 < 90% in either extremity at any reading
  • O2 90-94% in BOTH extremities on all 3 measurements
  • O2 difference > 3% b/t extremities on all 3 measurements
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20
Q

If a newborn meets 1 of the criteria for a (+) screening for coarctation, does this mean they have it?

A

NO

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21
Q

If a (+) screening test for congenital heart dz, what happens next?

A

pediatric cardiology evaluation
- Need to also rule out causes of hypoxemia

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22
Q

What labs are done to rule out causes of hypoxemia?

A
  • CXR
  • CBC
  • CMP
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23
Q

What imaging would look at the heart for a coarctation?

A

Echo

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24
Q

When should newborn tearing screening test be performed?

A

around 24hrs

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25
Q

What are the 2 types of hearing test for a newborn screening?

A
  • Otoacoustic emissions (OAE)
  • Automated auditory brainstem response (AABR)
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26
Q

Describe Otoacoustic emissions (OAE).

A

microphone placed in the ear canal detects sound waves generated in cochlea

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27
Q

Describe an automated auditory brainstem response (AABR)

A

sensors placed on head and neck detect action potentials in auditory nerve

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28
Q

Which type of hearing test is used in high risk newborns?

A

Automated auditory brainstem response (AABR)

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29
Q

Describe the 2 step screening for hearing issues.

A

Initial screen
- If (-), no further eval; monitor periodically at well child checkups
- If (+), repeat screening test in a few hrs
–> If (-) on 2nd screen, assume (-) but monitor closely
–> If (+) on 2nd screen, refer to audiologist

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30
Q

What are inborn disorders looking for on newborn screening?

A

abnormal level(s) of metabolites/ hormones/immune markers

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31
Q

How is the sample for testing obtained for inborn d/o?

A

blood from heel stick applied to test papers & sent to state labs.

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32
Q

When is the sample obtained for inborn d/o? Why?

A

close to discharge to allow max accumulation of markers

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33
Q

If the inborn d/o test is (+), what’s next?

A

will need further testing

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34
Q

List types of inborn d/o.

A
  • Errors of metabolism
  • Congenital hormonal disorders
  • Hemoglobinopathies
  • Immunodeficiencies
  • Other genetic disorders
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35
Q

What are the results of an error of metabolism?

A
  • accumulation of intermediate substance
  • product def or
  • toxic metabolite
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36
Q

What is an example of a dz cause by an error of metabolism?

A

Maple syrup urine dz

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37
Q

Pathophys of maple syrup urine dz.

A
  • enzyme def in pathway that breaks down BCAA (leucine, isoleucine, valine).
  • toxic metabolites cause distinctive smell of maple syrup in cerumen, urine, sweat
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38
Q

Errors of metabolism NOTE

A

Rare but serious genetic disorders

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39
Q

List the 4 categories of errors of metabolism.

A
  • AA d/o
  • CHO d/o
  • Organic acid d/o
  • FA d/o
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40
Q

Examples of amino acid d/o

A
  • Phenylketonuria (PKU)
  • Maple syrup urine disease
  • Homocystinuria
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41
Q

Testing for amino acid d/o

A

serum AA levels

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42
Q

Examples of CHO d/o

A
  • Galactosemia
  • Glycogen storage dz
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43
Q

Testing for CHO d/o

A

serum CHO levels

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44
Q

Examples of organic acid d/o

A
  • Propionic acidemia
  • Methylmalonic acidemia
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45
Q

Testing for organic acid d/o

A

serum levels

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46
Q

What tends to occur w/ organic acid d/o?

A

metabolic acidosis w/ presenting sign of tachypnea

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47
Q

Examples of FA d/o

A

acyl-CoA dehydrogenase deficiencies

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48
Q

Testing for FA d/o

A

serum levels

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49
Q

Describe genetic penetrance

A

It is the severity of the condition
- lower penetrance = takes longer for substance to accumulate
- higher penetrance = take less for substance to accumulate

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50
Q

Possible lab findings of acute decompensation w/ errors of metabolism

A
  • metabolic acidosis
  • Hyperammonemia
  • abnl LFTs
  • -cytopenias from bone marrow suppression
  • hypoglycemia
  • elevated LDH
  • elevated CPK
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51
Q

Describe labs findings for metabolic acidosis when acute decomposition in errors of metabolism.

A
  • organic acid d/o
  • low CO2 & HAGMA (adding an acid) on BMP
  • Order ABG to prove
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52
Q

Describe Hyperammonemia & S/Sx.

A

Result of ammonia (think encephalopathy)
- lethargy poor feeding
- irritable
- restless

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53
Q

Describe labs findings for abl LFTS when acute decomposition in errors of metabolism.

A

AST/ALT elevation due to irritation of liver

54
Q

Describe labs findings for acute decomposition in errors of metabolism.

A

WBC platelet are falling & anemia

55
Q

Why would CPK be elevated?

A

muscle breakdown problem

56
Q

Are all inborn errors are currently tested?

A

NO

57
Q

Examples of congenital hormonal d/o?

A
  • congenital hypothyroidism
  • congenital adrenal hyperplasia
58
Q

Describe Congenital hypothyroidism

A

Low levels of thyroid hormones lead to impaired cognitive and physical development

59
Q

Pathophys: Congenital hypothyroidism

A
  • thyroid dysgenesis (thyroid never formed)
  • disruption of TH synthesis
  • disruption of TSH receptor
  • pituitary/hypothalamic d/o
60
Q

Labs: Congenital hypothyroidism

A
  • screening: dependent on state
    –> Initial T4 test or initial TSH test or TSH/T4 combo test

–> All have false (-) & false (+) issues

61
Q

Describe Congenital Adrenal Hyperplasia

A

Impaired production of adrenal cortex hormones leads to adrenal insufficiency

62
Q

What is the most common reason for congenital adrenal hyperplasia?

A

21-hydroxylase enzyme

63
Q

What is the result of the accumulation of 17-hydroxyprogesterone?

A

adrenal glands often become enlarged (hyperplasia)

64
Q

Labs: Congenital adrenal hyperplasia

A
  • Newborn screening: high 17-hydroxyprogesterone
  • (+) lab findings: hypoNa+, hyperK+ (think Addison’s)
  • (+) testing: adrenal US–>
    Shows hyperplasia
65
Q

Example of a hemoglobinopathies?

A

Sickle cell disease/trait

66
Q

What is screened in sickle cell dz/trait?

A
  • homozygous sickle cell dz (HbSS)
  • sickle cell trait
  • sickle cell/beta-thalassemia
  • sickle cell/HbC
67
Q

Is the initial screening test for sickle cell dz/trait confirmatory?

A

No, will need confirmatory test

68
Q

Describe the SickleDex test.

A

Having 1 gene for sickling & will cause precipitation in medium
–> If cloudy–> sickle cell gene
–> If clear–> no sickle cell gene

–> Confirmatory Dx: electrophoresis

69
Q

How many types of genetic immunodeficiencies are there?

A

Over 300

70
Q

What do Congenital immunodeficiencies lead to?

A

early/severe/recurrent infx w/ high morbidity/mortality

71
Q

What is the only congenital immunodeficiencies screened?

A

Severe Combined Immunodeficiency (SCID)

72
Q

Severe Combined Immunodeficiency (SCID) causes…

A

Severe disruption of T cell development +/- B cell disruption
- Takes out the entire immune cell from working. Will still have some innate immunity

73
Q

Severe Combined Immunodeficiency (SCID): Newborn screening test for?

A

TREC level – T cell receptor excision circles

74
Q

What are TRECs?

A

small, circular pieces of DNA excised during development of T cells

75
Q

Describe results of TREC levels.

A

TRECs will be low in newborns w/ SCID
–> means low immune function

76
Q

Describe prehepatic neonatal jaundice

A
  1. Cause: Hemolytic anemia
  2. Liver is good, just overworked
  3. Clear biliary tree
  4. AST/ALT/Alk Phos normal
  5. High LDH & low haptoglobin
  6. High unconjugated (indirect)
  7. S/Sx: looks yellow, if affecting the brain–> lethargic)
  8. Tx: Phototherapy
    Worried >24hrs–>damage to brain
77
Q

Describe hepatic neonatal jaundice

A
  1. Cause: viral hepatitis, drug induced, autoimmune
  2. Liver is the problem
  3. High AST/ALT
  4. High unconjugated (indirect)
78
Q

Describe post-hepatic neonatal jaundice

A
  1. Cause: biliary tree atresia, sphincter of Oddi narrowed
  2. High unconjugated (indirect)
79
Q

Neonatal jaundice Diagnostic workup?

A

Obtain total & direct bilirubin measurements

80
Q

If direct bilirubin >15% of total, this means…

A

conjugated hyperbilirubinemia

81
Q

What are the causes of conjugated hyperbilirubinemia?

A

Causes:
- biliary atresia (Post heptatic), - hepatitis (hepatic)
- inborn error of metabolism (hepatic)

82
Q

If direct bilirubin < 15% of total, this means…

A

unconjugated hyperbilirubinemia

83
Q

Causes of unconjugated hyperbilirubinemia

A
  • hemolysis (hemoglobinopathies - inherited membrane defect (hereditary spherocytosis or oval spherocytosis)
  • bacterial sepsis
  • autoimmune
  • hemolytic dz of the newborn
84
Q

What is further testing for direct bilirubin <15% of total? (unconjugated hyperbilirubinemia)

A

Direct antigen test (Coombs test)

85
Q

Describe results of Direct antigen test (Coombs test) unconjugated hyperbilirubinemia.

A

DAT (+) = immune-mediated hemolysis
DAT (-)–> multiple other causes
- need to check Hct, retic count (2%), peripheral blood smear
–> Elevated Hct = polycythemia vera
–> Normal blood smear = blood loss, sepsis, drug rxn
–> Incr retic w/ abnl smear = hemoglobinopathy, membrane defect

86
Q

Describe Corrected Retic Count Formula

A

(Hct/45 x retic count) x 100

87
Q

Describe retic count values

A
  • <2% bone marrow production problem
  • > 2% destruction of RBCs
88
Q

Neonatal sepsis: Early onset happens when?

A

birth to 5 days

89
Q

What causes early onset neonatal sepsis?

A
  • Group B Strep
  • E coli
  • Listeria
90
Q

Workup for early onset neonatal sepsis?

A
  • CBC w/ diff
  • CMP
  • Blood cultures
  • CRP
  • LP/CSF analysis (rule out meningitis)
  • Other tests – UA, CXR, abd xray
91
Q

Neonatal sepsis: late onset happens when?

A

6 days to 1 month

92
Q

What causes late onset neonatal sepsis?

A

bacteremia or focal infection
- Same bacteria, + Klebsiella, S. aureus, Neisseria

93
Q

Workup for late onset neonatal sepsis?

A

Same as early onset, but need to look for focal infx (CXR, UA, blood cultures, etc)

94
Q

Which values are the same in Peds & Adults?

A
  • Na/Cl
  • BUN
  • Ca
  • Mg
95
Q

Which peds lab values decrease over time?

A
  • LFTs
  • K+
  • Phosphorus
96
Q

Which peds lab values increase over time?

A
  • Albumin (normal is 4)
  • Hgb
  • Cr
  • Glucose
97
Q

Which peds lab levels change in proportions?

A

WBCs
- initially lymphocytes predominant up to ~age 5, then neutrophils predominant

98
Q

How do Intellectual & physical development typically occur…

A

in sequential patterns

99
Q

For preterm infants, adjust for gestational age up to___ when assessing development.

A

2 years old

100
Q

Developmental milestones are subdivided into…

A
  • gross motor
  • fine motor
  • language
  • social milestones
101
Q

List screening tests for developmental milestones

A
  • Denver Developmental II
  • Parents Evaluation of Developmental Status (PEDS)
  • Ages & Stages Questionnaire (ASQ)
102
Q

What is evaluated at each visit & compared to standardized growth charts

A

height & weight

103
Q

Failure to thrive parameters

A

Persistent weight < 3% or fall from prior level; flattened or decr growth curve

104
Q

Causes of Failure to thrive

A
  • Anemia
  • bone marrow problem
  • kidney/liver
  • UTI
  • nephrotic syndrome
105
Q

Evaluation: Failure to thrive

A
  • CBC
  • CMP
  • UA
  • bone films
  • As appropriate – TSH, IGF-1, IgA [autoimmune (celiac dz)], ESR/CRP
106
Q

Obesity parameters

A

Weight is >95 percentile for age/height

107
Q

What tests are considered childhood screening tests?

A
  • Hgb
  • Lead
  • TB
  • Dyslipidemia
108
Q

Evaluation for Obesity

A
  • fasting glucose (type II DM), CMP (liver/kidney/electrolytes), lipid panel.
  • As appropriate – TSH (hypo), IGF-1 (GH), cortisol (Cushing synd)
109
Q

When to screen Hgb?

A

1 yo

110
Q

What hgb value needs further eval?

A

<11

111
Q

Causes of low Hgb in peds

A
  • not getting iron (hemoglobinopathy)
  • vegan/vegetarian diet
112
Q

When should evaluate for lead?

A

6, 9, 12, 18, 24 months & yearly thereafter

113
Q

How is lead measured?

A

blood

114
Q

What is measured next if lead levels are elevated?

A

measure zinc protoporphyrin (ZPP)

115
Q

If ZPP is elevated, what does this mean? & Tx

A

lead exposure is chronic–>consider chelation therapy

116
Q

What ages do you eval risk of latent TB?

A

1, 6, 12, 24 months & yearly thereafter

117
Q

What is next if patient is deemed at risk?

A

PPD test or CXR

118
Q

When should you not do a PPD test in child?

A

if vax or allergy

119
Q

When to eval for CVD risk factors?

A

yearly

120
Q

What are CVD RFs?

A

-smoke exposure
- HTN
- FHx
- CA
- DM
- systemic inflammatory dz

121
Q

If patient has no RFs, what is next?

A

check lipid panel once at ages 9-11yo & 17-19yo

before & after puberty

122
Q

If patient has 1 or more RFs, what is next?

A

check lipid panel at the time

123
Q

What is evidence (signs) of abuse?

A
  • bruising
  • fractures
  • burns
  • any unexplained visceral or intracranial injury
124
Q

If there is evidence/suspicion of abuse, what test are next?

A
  • retinal eval
  • skeletal survey
125
Q

What is a retinal eval looking for in regards to child abuse?

A

retinal hemorrhaging

126
Q

Describe a skeletal survey.

A
  • done on kids w/ limited communication
  • 21 separate x-rays
    –> Old fractures or damage
127
Q

Abuse signs: Abdo bruising/ tenderness is suggestive to what type of injury? How do you eval it?

A
  • visceral injury
  • CT abdo/pelvis
128
Q

Abuse signs: Neuro deficit is suggestive to what type of injury? How do you eval it?

A
  • Brain/cord injury
  • MRI
129
Q

Poss. not abuse: Bruising w/ petechia is suggestive to what? How do you eval it?

A
  • bleeding disorder
  • PT/INR & PTT, CBC (platelets)
130
Q

Poss. not abuse: Multiple fx, low suspicion of abuse is suggestive to what? How do you eval it?

A
  • bone d/o
  • Vit D (low), CMP, EXA, Ca+ (low), Alk Phos, PTH, Mg (low)