Great work! This patient is a nulliparous woman who has developed hypertension at 28 weeks gestation. She has also developed proteinuria with >300mg on a 24 hour urine collection, leading us to a diagnosis of preeclampsia.
Hypertension (HTN) in pregnancy is defined as having a blood pressure (on multiple measurements) ≥ 140/90. The timing of onset of hypertensive disorders of pregnancy is key to making the correct diagnosis. Chronic hypertension is the presence of HTN prior to 20 weeks gestation. A patient has gestational hypertension when hypertension develops after 20 weeks gestation. Patients with preeclampsia have the onset of hypertension after 20 weeks gestation along with additional features as outlined below. Eclampsia includes the additional presence of seizures. The infographic below summarizes the progression from gestational HTN to eclampsia.
The pathophysiology of preeclampsia is not understood completely, but it is thought to be due to placental malperfusion which result from abnormal remodeling of maternal spiral arteries. In preeclampsia, circulating maternal serum levels of soluble fms-like tyrosine kinase 1 (sFlt-1) are increased, and placental growth factor (PlGF) levels are decreased. Release of angiogenic and antiangiogenic molecules from the placenta leads to generalized endothelial activation in the mother – ultimately leading to the clinical manifestations of preeclampsia such as capillary leak (edema), thrombosis (and subsequent thrombotic microangiopathy), and inflammation. Preeclampsia is a multisystemic, heterogenous disease that is associated with high risk of perinatal and maternal morbidity and mortality.
Kidney biopsy is rarely needed for diagnosing preeclampsia, and is only really considered to rule out other causes of kidney injury in pregnancy such as glomerulonephritis. The diagnosis relies on clinical and laboratory features.
AST or ALT >70 U/L
Lactate dehydrogenase (LDH) > 600 U/L
Superimposed preeclampsia can occur in women with chronic HTN. The same diagnostic criteria for preeclampsia apply, except hypertension is discovered prior to 20 weeks gestation.
The definitive treatment for preeclampsia is delivery, specifically the removal of the placenta. Kidney-specific indications for delivery include significantly worsening kidney function or severe refractory hypertension. Interestingly, proteinuria is not a good predictor of preeclampsia severity.
Take a look at some additional resources below:
- Gonzalez Suarez, M., Kattah, A., Grande, J., & Garovic, V. (2019). Renal Disorders in Pregnancy: Core Curriculum 2019. American Journal of Kidney Diseases : The Official Journal of the National Kidney Foundation, 73(1), 119-130.
- Mayrink J, Costa ML, Cecatti JG. Preeclampsia in 2018: Revisiting Concepts, Physiopathology, and Prediction. ScientificWorldJournal. 2018:6268276.
- August, P. (2013).Preeclampsia: a “nephrocentric” view. Advances in Chronic Kidney Disease, 20 (3), 280-286.
Thanks to Derian Lai (@GlomeruLai) for this case contribution!