Thread by @amyaimei

Is being pregnant magical🌟?
I’m not so sure, but let’s give OB a Nephrology twist. 🍼🐣

#nephtwitter #obtwitter #endotwitter #reallythekidneysarethecoolest #medtwitter #tweetorial

Why do you gain weight when you are pregnant?

The average woman ⬆️gains a plasma volume of 1250 mL (an increase of 45-55%).

Significant lab values changes include
- Plasma Na ⬇️reduced by ~ 5 mmol/L
- Plasma osmolality ⬇️reduces by ~10 mOsm/kg
- Cr ⬇️decreases by 0.3 mg/dL due to increased GFR among other changes

There is an entire milieu of hormone changes during pregnancy🤰. Some are natriuretic and some are anti-natriuretic.

Sources: Comprehensive Clinical Nephrology Chapter 42, pubmed.ncbi.nlm.nih.gov/22879432

🧂Na retention is mediated through
- ⬆️increases in aldosterone and cortisol through the uteroplacental RAS
- 🔄degradation of progesterone.

pubmed.ncbi.nlm.nih.gov/24089380
pubmed.ncbi.nlm.nih.gov/19171690/

💧H2O retention occurs during pregnancy because of
- ⬆️Increased Na🧂retention
- ⬆️Increased ADH due to de decreased ADH threshold

Although the placenta makes high levels of ⬆️vasopressinase, the liver has an increased capacity to break it

pubmed.ncbi.nlm.nih.gov/30638905

❓But, what if the liver’s degradation capacity is lost? What disease state could you see?

Correct! 🥤Gestational Diabetes Insipidus (DI) #NephPearls

🔑Worse later in pregnancy (larger placenta)
🔑Resolves weeks after delivery
🔑Risk of polyhydramnios
🔑Risk factors: impaired hepatic vasopressinase degradation from preeclampsia, HELPP, or acute fatty liver disease

🥤DI during pregnancy🤰 can be from multiple etiologies.

If persists weeks post-partum think about those other causes.

Management during pregnancy is 🌟empiric DDAVP🌟 because it is ✖️NOT degraded by vasopressinase

pubmed.ncbi.nlm.nih.gov/30638905
pubmed.ncbi.nlm.nih.gov/27172867

🧐But wait ….if pregnant women have
⬆️high aldo
⬆️increased plasma volume
⬆️increased angiotensin II (AII)

❓Why aren’t they hypertensive?

🤰Pregnant women need REALLY REALLY HIGH levels of AII
⬇️AT1 receptors are downregulated thus reducing AII sensitivity
➕Plus relaxin and ANG1-7 result in vasodilation

pubmed.ncbi.nlm.nih.gov/30705695
pubmed.ncbi.nlm.nih.gov/19171690/

❓Why does hypertension occur in preeclampsia?

It’s definitely multipronged, but ultimately related to dysregulation in RAS system.

Preeclamptic moms have ⬇️lower than expected levels of
- renin
- angiotensin I
- aldosterone

And ⬆️increased sensitivity to angiotensin II

pubmed.ncbi.nlm.nih.gov/19657323
pubmed.ncbi.nlm.nih.gov/18687466

Increased sensitivity may be due to AT1 receptor sensitivity/activation through AT1 autoantibody (AT1-AA)

The result is
- endothelial damage
- HTN
- thrombin generation

pubmed.ncbi.nlm.nih.gov/21266264
pubmed.ncbi.nlm.nih.gov/26292986

❓What is your blood pressure goal in a pregnant woman?

BP goal should be less than 🌟140/90 mmHg🌟#NephPEARLS

In preeclampsia if there is BP > 160/110 or end organ dysfunction, you should consider delivery.

❓But, what if you have a patient has hypokalemia and significant hypertension during pregnancy? What disease state should you consider?

Well done! Geller's (activating mineralocorticoid receptor mutation) should be considered. #NephPearls

🔑AD inheritance
🔑HTN is from 🌟progesterone activation of MR receptor
🔑Can be worsened by spironolactone
🔑Treatment is BP management and delivery

pubmed.ncbi.nlm.nih.gov/29758100

What did we learn?

📌In 🐣🍼pregnancy, RAS and ADH increase ➡️ increase plasma volume
📌Gestational DI 🥤occurs from placental production of vasopressinase
📌Preeclampsia is due to dysregulation of RAS. BP goal < 140/90
📌Pregnancy + progesterone + HTN ➡️ think Geller’s (AMR)