Along with fats and sugars, proteins form the main building blocks for our bodies (Gupta, 2015). The right amount of protein is important in our diets, for growth and repair. Protein is present in the blood and healthy kidneys should only filter tiny (trace) amounts into the urine as most protein molecules are too large for the glomeruli of kidney to filter (Mora‐Fernández et al., 2014).
Several proteins can be found in the urine, but the most significant is albumin. Protein in the urine is not usually obvious, but can be detected by a simple dip-stick test, or sometimes by more sensitive laboratory tests such as routine urine examination, creatinine clearance and blood urea nitrogen tests (Rodriguez-Thompson & Lieberman, 2001).
Proteinuria is a condition resulting from increased urinary protein in amounts exceeding 0.3 g in a 24 hour urine collection or in concentrations more than one(1) gram per liter (Gupta, 2015). When protein excretion exceeds these levels in pregnant women it is considered abnormal and a sign of pre-eclampsia after twenty (20) weeks gestation (Hutcheon, Lisonkova, & Joseph, 2011).
However, proteinuria before pregnancy or before 20 weeks gestation is considered a sign of existing renal disease (Lulzime & Mirela, 2015). The presence of protein in the urine can act as an indicator that the kidneys are not functioning well. In the early stages of the condition, patient does not have any symptoms (Listman & Schurman, 2014).
Therefore, it is often detected accidentally when performing urinalysis and chemistry for other reasons. As the condition worsens, the patient may start showing symptoms (Roberts, Pearson, Cutler, & Lindheimer, 2003). When proteinuria is present, it is either due to disease within the bladder or lower urinary tract or disease within the part of the kidney called the glomerulus; the part of the kidney where blood is filtered to make urine.
In pregnancy the renal hemodynamic changes (mechanism that describes the flow of fluids such as blood) mean that higher amount of colloids and solute pass by the glomerular barrier per unit time. Moreover, there are changes in glomerular permeability and altered tubular reabsorption of filtered proteins that may result in increased excretion of protein.
Four mechanisms for proteinuria are known; due to the abnormal trans-glomerular passage of proteins as a result of increased permeability of the glomerular capillary wall, increased plasma concentration of proteins, addition of proteins to the tubular fluid and the impaired reabsorption by the epithelial cells of the proximal tubule.
The presence of proteinuria is seen as a possible indication of many complications in pregnancy, from urinary tract infection to chronic renal disease and it remains central to the diagnosis of pre-eclampsia in a hypertensive pregnancy.
The incidence of proteinuria arising in pregnancy varies according to parity, Body Mass Index (BMI), high alcohol intake, age and underlying medical disease. Proteinuria can be caused by the pregnancy itself, or may exist before conception (being unrelated to the pregnancy).
However, as pregnancy may be the first point of medical contact for many women, pre-existing proteinuria may be first detected at this time. Hypertension with proteinuria is associated with increased fetal and maternal morbidity, especially if occurring in the third trimester of pregnancy. Quantification of proteinuria in the pregnancy is important not only for making diagnosis, but also for predicting maternal and fetal outcome (Lulzime & Mirela, 2015).
In pregnant women, the main aim is to have normal delivery but patients with proteinuria quite often develop progressive disease which ends up in the need for iatrogenic delivery. In normal pregnancy there is an increase in total urinary protein and albumin excretion, especially notable after 20 weeks (Lulzime & Mirela, 2015).
The high incidences of proteinuria in pregnant women have consequences on the mother and fetus. Proteinuria may suggest kidney damage and may eventually lead to its failure.
Amyloidosis, a complication which can result from proteinuria may eventually lead to weight loss, anemia and immune system disorders to the mother and the child as well (WHO, 2008). Damage to the kidney may lead to soft bone formation in fetus due to decrease production of vitamin D in the mother. Some of the risk factors include drug use, strenuous exercise, kidney disease, high blood pressure and diabetes.
Proteinuria is common in diabetics and hypertensive and a forerunner to diabetes. Proteinuria often does not present any symptoms, so it can exist undetected unless you undergo urinalysis. If protein excretion is high, urine will appear foamy. You may also experience other symptoms related to the underlying condition that is causing proteinuria such as edema.
The complications of proteinuria depend on the underlying cause of the condition. Generally, protein in urine is associated with kidney disease, so kidney function may begin to decline over time. People with proteinuria may also experience high blood pressure and high cholesterol, which can further damage the kidneys if not managed properly.
By: (Kelly et al., 2017)
Kelly Michael Agbesi
Yakubu Umar Farouk