Nephrotic proteinuria with pre-eclampsia

Multiple pathologies in the kidney biopsy of a recently pregnant woman

We report a 42-year-old woman with underlying hypertension, mild renal dysfunction and proteinuria who presented as an obstetric emergency with uncontrolled hypertension and nephrotic syndrome. The rapid deterioration in her kidney function and worsening of her symptoms led to an urgent termination of her twin pregnancy. Although a clinical improvement was noticed within 10 days, the persistently elevated serum creatinine required further evaluation. A kidney biopsy showed changes consistent with acute tubular necrosis and resolving preeclampsia superimposed on focal segmental glomerulosclerosis and hypertensive kidney disease. The importance of a kidney biopsy in confirming clinical suspicions and determining patient prognosis is emphasized.

GLOMERULONEPHRITIS AND THE NEPHROTIC SYNDROME IN PREGNANCY

Glomerulonephritis (GN) may be manifest clinically in several ways. It may be asymptomatic and associated with only minor urinary dipstick abnormalities, GN may present with one of the classic renal nephritic or nephrotic syndromes, or may be associated with progressive chronic kidney disease with hypertension and the gradual development of uraemia, or it may present with fulminating life threatening illness with severe acute kidney injury. The development of GN may indicate a primary renal limited disease, or may be secondary in association with systemic diseases such as systemic lupus erythematosus (SLE), myeloma, infections or diabetes. Although immunological abnormalities underlie the development of many forms of GN, precise pathogenic mechanisms remain unclear and diagnostic labels may simply reflect a description of the glomerular histological changes observed (Table 1).

Dilutional hyponatremia in pre-eclampsia

OBJECTIVE

The objective of this report is to describe a defect in water metabolism, characterized by hyponatremia, in patients with pre-eclampsia-induced nephrotic syndrom.

STUDY DESIGN

This was an observational study of 3 women.

RESULTS

Hyponatremia was observed in 3 women with pre-eclampsia characterized by various extrarenal manifestations, as well as by nephrotic syndrome with normal or nearly normal renal function. Restriction in water intake partially corrected hyponatremia before delivery in each case, and no complications were observed in the neonates. The mechanism of impaired excretion of water in these patients is proposed to involve persistent and inappropriate production of vasopressin through stimulation of the nonosmotic mechanism for vasopressin secretion in response to a reduction in effective plasma volume.

CONCLUSIONS

These results indicate for the first time that women with pre-eclampsia are, at least when nephrotic, at risk for development of dilutional hyponatremia, which can cause neurologic complications that simulate those of eclampsia.

Proteinuria and outcome of 444 pregnancies complicated by hypertension

The purpose of this study was to determine the role of proteinuria on pregnancy outcome in 444 hypertensive women with singleton pregnancies. The patients were divided into three hypertensive groups: 98 with chronic hypertension, 199 with nonproteinuric gestational hypertension, and 147 with proteinuric preeclampsia and chronic hypertension with superimposed proteinuric preeclampsia. The presence of increased proteinuria (greater than 0.3 gm/L) predicted an adverse pregnancy outcome. Furthermore, the majority of small-for-gestational-age infants occurred in the group with proteinuric preeclampsia (52%), whereas the rate of small-for-gestational-age infants was 18% and 12% in the group with nonproteinuric gestational hypertension and chronic hypertension, respectively. The group with chronic hypertension did not show any increased risk for fetal outcome. Perinatal mortality rate was extremely poor in the group with proteinuric preeclampsia at 129 per 1000, four times higher than those of the other two groups.

Pre-eclampsia as a multi-system disease

Pre-eclampsia cannot be defined precisely by clinical signs which are just readily detectable secondary features of the primary abnormality within the uterus. The multisystem sequelae could be thought of as a secondary maternal adaptation, with the large variation in clinical presentation reflecting variable susceptibility of maternal target organs. The changes may be characteristic of pre-eclampsia but are not specific and therefore reflect a process rather than a discrete disease entity. Because the pathogenesis is so controversial it is not surprising that views on management differ so much.

The clinical spectrum of preeclampsia

Though classically a disease of the near term nullipara, the chameleonlike presentation of preeclampsia makes the diagnosis at times difficult and in most circumstances presumptive. A high index of suspicion is important. Early and frequent prenatal examinations coupled with laboratory parameters should reduce diagnostic error.

Normal and abnormal aspects of proteinuria. Part I: Mechanisms, characteristics and analyses of urinary protein. Part II: Clinical considerations

Part I highlights the mechanisms of glomerular filtration and tubular reabsorption of plasma proteins, selected characteristics of urinary proteins based upon electrophoretic properties and recent advances in clinical laboratory analysis of proteinuria. Both structural characteristic of the glomerular capillary wall and molecular properties of plasma proteins are important determinants of glomerular filtration. Proteins filtered by the glomerulus subsequently appear in urine only after escaping the efficient mechanisms of tubular reabsorption. Albumin is one such protein and constitutes the major protein in normal urine although trace amounts of alpha, beta, and gamma globulins are also detectable. Several techniques of protein analysis have thus been developed to specifically measure albumin as well as other plasma proteins. Other methods have been adapted to measure total urinary protein content enabling the clinician to readily monitor renal function in health and disease. The second part of this review will consider conditions associated with proteinuria in both asymptomatic individuals and patients with renal disease. Asymptomatic proteinuria encompasses states of excess protein excretion during conditions of orthostasis, exercise, travel to high altitude of fever. Proteinuria during renal disease has received considerable interest as a means to monitor kidney function. It is therefore classified according to the type of damage incurred: (1) glomerular-type where large molecular weight proteins are excreted (2) tubular-type where small molecular weight proteins are excreted and (3) mixed-type characterized by both large and small molecular weight proteinuria.

Fetal outcome in hypertensive disorders of pregnancy

Fetal outcome was evaluated in 157 hypertensive pregnant women whose underlying disease had been established by renal biopsy. The patients had pathologic diagnoses of preeclampsia (95), nephrosclerosis (23), nephrosclerosis with superimposed preeclampsia (13), interstitial and tubular nephropathy (seven), and normal findings (six). Pregnancy outcome in this selected group of patients was extremely poor, with the perinatal mortality rate being 134 per 1,000. There were 21 perinatal deaths; three quarters of these were stillbirths, and most were encountered below the fiftieth weight percentile and before 30 weeks' gestation. In addition 22% of the infants were small for gestational ages, and 40% of the infants were born before term. Most of the perinatal mortality (81%) was in women with preeclampsia. The worst fetal outcome was encountered in multiparous preeclamptic women, over 50% of whom manifested nephrotic-range proteinuria during pregnancy. Despite the presence of hypertension throughout most of their gestation, women with nephrosclerosis alone had the best fetal survival rate.