chem 10

gestation age vs conception age

counted from 1st day pf last period, preg 40 weeks vs counted from fertilization (2 weeks less)

trimesters

1- conception to week 12, 2 week 13-26, 3 week 26 to delivery

ovulation

fertilization in the fallopian tube> sygote> blaastocyst> implantation in uterine wall

embryo

organs form (up to 10 weeks), fetus growth and maturation after

term

38-42 weeks, pre= before 37 weeks

placenta

oxygen, nutrients, hormones between pt and fetus, made from trophoblast cells outside blastocysts, lost after delivery

placenta hormones

hCG, progesterone, estriol, human placental lactogen, return to prepreg levels post delivery

trophoblast

makes hCG> keeps corpus luteum making progesterone until placenta takes over

progesterone in labor

relaxed uterine smooth muscle (no contractions), falls before labor

estrogen in labor

high contraction receptors on uterine muscle

oxytocin (posterior pituitary) in labor

triggers uterine contractions

human placental lactogen hPL

insulin resistance> more glu for fetus, shifts pt towards burning fat for energy, if cannot make enough insulin to balance increase= GDM

plasma vol during maternity

increases causing dilutionally low in hct alb and total protein

RAAS activated during maternity

high aldosterone> sodium and water retention, low plasma osmolality (thirst and vasopressin threshold are lower)

slight rise in potassium during maternity

progesterone effect, usually still in ref interval

GFR in maternity

50% higher> low serum creatinine bc more is filtered, BUN and uric acid, causes glucosuria and urine protein up to 300

kidney in maturnity

glucosuria (less reabsorded by PCT), urine protein rises slightly (up to 300/day) usually in ref interval

blood gases during maternity

hyperventilation (low pCO2 and high pO2), kidneys excrete more bicarbonate (18-22) lowering it, fully compensated resp alkalosis

estrogen during maternity

liver makes more TBG increasing TT4 and T3, FT4 is norm

affect of hCG resembling TSH

mild thyroid stimulation> N-low TSH, 1st trimester

prolactin lipids and cortisol during maternity

10x high by term

FSH and LH during maternity

suppressed by estradiol, progesterone, and inhibin

ACTH, cortisol and free cortison during maternity

increased (cortisol 3x by 3rd tri), can mimin cushings (striae, high bp, impaired glucose tolerance), diurnal variation continues

insuline 1st trimester vs 2/3

high insulin sensitivity bc storing fuel vs insulin resistance hPL, GH, cortisol, progesterone, prolactin) increasing plasma glu for fetus

glucose vs lipids during maternity

fasting slightly low bc fetus is continuously using it vs trig and LDL high

during maternity high demand for

iron, folate, vit B12, and iodine

increased need for iodine during maternity

due to transfer to fetus and high urinary loss, def can cause goiter

total calcium during maternity

low bc alb low, ionized is norm (better test), absorption and urine amount increases (risk of kidney stones)

low intake of Ca during maternity

fetus draws from maternal skeleton, take prenatal vitamins

hCG summary

tests target beta subunit, doubles every 2 days, peaks at 8-12 weeks, lower plateau the rest of preg, 7-60 days post preg returns to norm

urine point of care POC hCG

qualitative lateral flow cassette, neg or pos, waived- home preg test, detection limit- 20, false pos- misreading drugs contamination

serum quantitative hCG

auto sandwich immunoassay, ref by gestation week, nonpreg 0-9 higher after age 55

serum quantitative hCG false pos

heterophiles ab- rheumatoid factor, IgA def; HAMA, high dose hook, kidney failure, injected hCG, misread

hook effect

very high hCG saturates both assay antibodies, falsely low or neg; dilute and repeat

serial hCG

norm rise- developing preg, slow rise/plateau- nonviable/ectopic, falling- preg loss follow until nonpreg level, 2 MoM higher- down syndrome

alpha fetoprotein AFP

glycoprotein mady by yolk sac then fetal liver, crosses into maternal blood, adjust for age weight ethnicity diabetes and fetus #

alpha fetoprotein AFP testing window

2nd tri 15-20 weeks bc maternal serum MS-AFP rises week14-32 (ref 0.5-2)

multiple of the median MoM for AFP test

pt result / median for sam gestational week

high MS-AFP

open neural tube defect NTD, abdominal wall defects, multiple pregnancy, fetal distress or death, underestimated gestational age

low MS-AFP

down syndrome, trisomy 18

AFP sandwich immunoassays

enzyme-labeled, microparticle, bead, radioimmunoassay (older method), use same lab fro serial screenings (methods differ)

AFP specimens

serum, amniotic fluid, urine, stable 7 days at rt

amniotic fluid AFP and acetylcholinesterase AChE

when MS-AFP is high and ultrasound doesn’t explain, amniocentesis (high AFP + AChE= open NTD), norm absent, polyacrylamide gel electrophoresis

fetal blood affect on amniotic fluid AFP and AChE

falsely increases, test for hgb, or chromosome analysis

unconjugated estriol uE3

marker of fetoplacental health, rises about 20-25% per week in 2nd tri, low in down synd, trisomy 18, fetal demise, growth restric, preeclampsia

unconjugated estriol uE3 false increase

standing at rt or refrigerator temp, due to conjugated breaks down, falsely norm hides down syndrome or trisomy 18

inhibin A screening

glycoprotein from fetoplacental unit, inhibits FSH, high in down syndrome, with triple screen= quad, stable in serum, specific for dimeric

preg associated plasma protein A PAPP-A screening

placenta glycoproteins, useful in 1st tri, low in trisomy 21 and 18, with hCG and nuchal translucency ultracound

triple and quad screen

AFP + hCG + uE3, inhibin A in quad, 2nd tri, pos (genetic counseling+ dx testing- amniocentesis)

triple and quad screen risk estimate

combined with age, weight, gesta, diabetes, fetus #

if down syndrome sus

use quad screening

triple and quad screen results

high AFP= open NTD, low AFP uE3 high hCG inhibin A= down syndrom, low AFP uE3 hCG= trisomy 18

progesterone screening

low or falling= threatened or spontaneous abortion

gestational diabetes mellitus GDM screening

24-28 weeks, 50g glucose 1hr >140, OGTT- 3 hr >190, 100g 8-12 fast 95 1 hr 180, 2 hr 155, 3 hr 140, dx if 2 or more OGTT values above cutoff

gestational diabetes mellitus GDM risks

fetus- large baby (macrosomia), newborn hypoglycemia, breathing prob, pt- type 2 diabetes later in life

fetal fibronectin fFN

protein glue in amniotic fluid and placenta uterus, low in secretions until term, swab if preterm sus, pos= delivery in 7-14 days, neg strong NPV

neural tube defects NTD

failure to close at 4 weeks gestation, spina bifida (myelomeingocele), anencephaly, encephalocele, folic acid before conception lowers risk

open NTD

not covered by skin, fetal AFP leaks into amniotic fluid> high MS-AFP

NTD workup

high MS-AFP> ultrasound> amniocentesis (amniotic fluid AFP + AChE)

down syndrome trisomy 21

most common serious chromosome abnorm, 5% by translocation, risk rises with mom age, intellec disabili, low muscle, heart defect, flat facial, confim with amniocentesis (chromosome analysis)

down syndrome trisomy 21 2nd tri vs first

low AFP uE3 hCG vs low PAPP-A

trisomy 18 (edwards syndrome)

extra copy of chromosomes 18, usually fetal loss, 2nd tri- low AFP uE3 hCG, 1st- PAPP-A low, growth restriction on ultrasound, confirm by amniocentesis

isoimmunization

maternal IgG ab cross placenta destroys fetal red cells (HDFN), classic case D neg pt with D pos fetus, fetal anemia> heart fail edema> hydrops fetalis

preterm delivery risk to newborn

resp distress syndrome RDS, too little lung surfactant, give steroids before delivery> fetal lungs more surfactant, fetal fibronectin assesses risk

preeclampsia

new hypertension (sys 140 dis 90) + proteinuria >0.3 (edema) in 2/3 tri, eclampia (seizure), liver & organ injury, high pee proteins, 2nd tri high inhibin A, low uE3, 1st low PAPP-A

preeclampsia severe lab results

plts <100,000, AST and ALT doubled, if also hemolysis= HELLP syndrome

eclampsia treated with magnesium sulfate

reflexes (creatinine high), breathing 12, low urine- toxicity >9, therapeutic is 5-8, stop Mg, give calcium gluconate

hyperemesis gravidarum

severe persistent vomit, at 4-8 weeks, dehydration, ketonuria, weight loss, low K+, high hCG (1st tri, twins), low TSH

hyperemesis gravidarum wernicke encephalopathy

prevent with IV fluids and vitamins, thiamine

ectopic pregnancy

implantation outside uterus (fallopian tube), 2% of pregs, vag bleeding, lower abdom pain, adnexal mass, tube rupture> internal hemorrhage

ectopic pregnancy risk factors

prior pelvic inflam disease or STI, prior ectopic, tubal surgery, assisted reproduction

ectopic pregnancy workup

B-hCG pos> transvag ultrasound (no preg in uterus), serial hCG rises slow or plateaus

point of care testing POCT advantages

fast turnaround TAT, small sample vol, fewer steps (less errors), portable, lower cost (shorter stay, fewer visits)

POCT disadvantage

higher cost than lab test, less QC training, more to manage/validate, variable, less documentation, expiration date/lot tracking at many sites

CLIA

depend on complexity not location, required

mod-high test complexity

personnel qualifications, proficiency testing, inspections, QC, QA, maintenance, can be POC

provider performed microscopy procedures PPMP

moderate complexity, bright field or phase contrast by physician, dentist, nurse, PA on specimen to liable to transport, no QC

certificate of registration

temporary/ new lab, non waived testing until survey shows compliance

certificate of compliance

issued after gov inspection finds lab compliant

lab role in POCT

responsible for quality management, multidisciplinary committee (lab phys nurse admin) review new POC requests, monitor sites, feedback

director of POCT program

physician or doctoral scientist, responsible for analytic performance, policies, and regulatory compliance, can also be consultants

tech consultant vs clinical

scientific oversight (mod complexity) vs gives advise (mod)

glucose meters

accuracy and precision concerns lead to insulin dosing errors, FDA tightened standards for over the counter, hct can affect

POC glucose and HbA1c

best for monitoring and screening, not tight glucose control at bedside

internal vs external QC

check test system integrity or electronics daily vs control material tested like pt sample testing whole process

QC lockout vs operator lockout

blocks pt testing until required QC is done and acceptable vs blocks workers with expired training

strip or cartridge + reader for quantification

glucose, blood gases, electrolytes, HbA1c

handheld or small benchtop analyzer

blood gases, electrolytes, hgb, bilirubin, cbc

lateral flow immunoassay

ab strip with visible line (urine hCG)

growing areas

intraoperative parathyroid hormone (PTH), creatinine and cardiac markers in the emergency department, infectious diseases

glucose application

highest vol POC test

middleware

data manager, can serve many devices from diff manufacturers, sends to LIS> EMR, pt operator device ID (time specimen type units errors)

unidirection vs bidirections

reads only from devices vs reads AND sends operator lists, reagent lots, and pt infor to devices

Which agency assigns the complexity category (waived, moderate, or high) to a test?

FDA