Maternal & Fetal Health - Sood Flashcards
Why and how do T3 & T4 levels increase during pregnancy?
- Increased thyroxin binding globulin (TBG) levels cause a decrease in free T3/T4
- Decreased clearance of TBG (due to estrogen[?])
- Increased liver production of TBG
- Pituitary senses low free T3/T4 and increases TSH production
- Placenta also stimulates T3/T4 release via hCG
How would placental production of hCG affect TSH levels?
hCG stimulates T3/T4 release from the thyroid, which would decrease TSH release via negative feedback.
Review:
Name three thyroid antigens which autoantibodies can be produced against in the context of autoimmune thyroid diease. Which antigen can have blocking and stimulating antibodies raised against it?
- Thyroglobulin (Tg, aka colloidal antigen)
- Thyroid peroxidase (TPO)
- TSH receptor
- Abs can be blocking (e.g. autoimmune thyroiditis) or stimulating (Graves’)
How common are Tg or TPO autoantibodies in women of child-bearing age?
10-20%
[Wiki states Hashimoto’s has a prevalance of ~1:1000. The lecture goes on to state that most women with autoabs do not suffer sufficient thyroid destruction to cause hypothyroidism. So it seems having the autoabs does not imply a clinically significant disease.]
What are the side effects of iodine deficiency in a pregnant woman?
- Goiter in the mother
- If severe, neurocognitive impairment / mental retardation / deaf-mutism in the offspring
- (Keep in mind - higher dietary requirement in pregnancy)
What complications of pregnancy are noted in women with Tg or TPO autoabs?
Associated with pregnancy loss, recurrent miscarraiges, and preterm delivery
Your patient is a 27yo pregnant female in her 1st trimester of pregnancy, presenting with heat intolerance, palpitations, increased sweating, and anxiety. She denies nausea or vomiting. You suspect Graves’ disease, but anti-TSH receptor autoAbs are negative.
- What other process might be responsible for her symptoms?
- If the patient instead presented with a CC of nausea & vomiting, and you saw that she was no longer gaining weight at a normal rate despite her pregnancy, what would you suspect?
-
Gestational Hyperthyroidism
- Transient & observed in first half of pregnancy
- 1-3% of pregnancies
- Due to excess production or activity of hCG
-
Hyperemesis Gravidarum
- Nausea, vomiting & weight loss
- 0.05% to 1% of pregnancies
What are the symptoms of a thyrotoxic crisis?
What are potential consequences of this condition?
- aka Thyroid Storm
- fever
- tachycardia
- seizures
- restlessness / confusion
- diarhhea
- vomiting
- cardiac arrythmia
- Can result in shock, coma, or death
What are 5 potential complications of Grave’s disease in the context of pregnancy?
- Increased abortion risk
- Preterm labor
- Low birth weight
- Stillbirth
- Preeclampsia
What advice would you give a young woman recently diagnosed Graves’ Disease if she told you she planned on becoming pregnant soon?
- The disease needs to be treated several months before pregnancy
- Circulating autoAbs that cross the placenta pose serious risk to the fetus
- These Abs persist for months following surgical or radioactive thyroid ablation
What is the cause of Sheehan Syndrome?
Where is it most common?
- Ischemic injury to the hypothalamic-pituitary axis following severe hemorrhage and hypotension at delivery
- Susceptibility is due to increased size of the pituitary during pregnancy and the low-flow, low-pressure nature of the portal circulation
- Most common in parts of the world where deliveries are not performed in healthcare facilities
If a woman developed Sheehan Syndrome shortly following delivery, what symptoms might she notice quickly and thus present with?
- Failure of lactation
- Failure of hair growth over areas shaved for delivery
- Poor wound healing following a cesarean delivery
- Weakness
Why does some healthy pregnant women develop a temporary loss of vision in the outer halves of their left and right visual fields?
Bitemporal hemianopia
- Lactrotroph cells of pituitary increase 20-60% by the 3rd trimester
- Entire pituitary gland also increases in wieght by 30%
- Increased size places pressure on the optic chiasm, which causes the visual disturbance.
In general terms, what are the major hemodynamic (vessel) changes of pregnancy?
-
Increased capacity and reduced resistance
- Decreased vascular resistance
- Arterial compliance
- Vascular capacitance
What changes in renal function occur during pregnancy?
(Hint: Think of the hemodynamic changes)
- Increased renal blood flow
- Increased glomerular filtration
-
Increased RAAS activation
- Note: causes reduced response to infused pressor compounds
Define gestational hypertension.
Typical criteria of HTN (>140mmHg systolic and/or >90mmHg diastolic) in a pregnant woman.
What are ~7 symptoms of preeclampia?
What additional symptom makes for a diagnosis of eclampsia?
- Severe HTN (>160mmHg systolic / >110mmHg diastolic)
- Proteinuria (not always present but useful in making the Dx when present)
- “End organ dysfunction”
- Visual distubances & Headaches
- Epigastric pain
- Thrombocytopenia
- Abnormal liver function
- Seizures in the context of preeclampsia makes for a Dx of eclampsia
What are the defining criteria of HELLP syndrome?
- Severe HTN plus:
- Hemolysis
- Elevated Liver enzymes (hepatic dysfunction)
- _L_ow _P_latelet count (thrombocytopenia <100,000/ul)
What are **seven **potential maternal sequelae of severe HTN disorders during pregnancy?
- Pulmonary edema
- Stroke
- Liver failure
- Renal failure
- Seizures
- Death
- Long-term risk to develop HTN and/or related disorders (outside of pregnancy)
What are four potential fetal sequelae of severe HTN disorders during pregnancy?
- Growth restriction in utero and small birth weight
- Oligohydramnios (reduced amniotic fluid)
- Indicated preterm delivery
- Long term risk to develop metabolic and/or cardiovascular disorders