Understanding acute kidney failure

What you need to know:

  • Patients with diabetes, high blood pressure, advanced age, or those admitted for other serious conditions should be monitored closely.
  • Occasionally, acute kidney failure causes permanent loss of kidney function (end-stage renal disease) requiring permanent dialysis.

Recently, media reported some interesting mortality data at Kenyatta National Hospital (KNH) indicating that kidney problems (47 per cent) and pregnancy-related illnesses (38 per cent) accounted for most of the deaths among about 21,000 people who sought care at the facility between 2014 and 2015.

Now here is the mystery: while the number of patients with renal conditions who sought care at the hospital during the period was lower compared to patients with pregnancy- and birth-related conditions (18,292), why were more patients dying from renal causes?

Dr John Ngigi, the head of the renal unit, was reported as saying that the two conditions could be related as a result of what he called obstetric “acute kidney failure”. I could not agree more with him on this one. In epidemiology, we call this phenomenon a confounding variable. Confounding factors, if not controlled, cause bias when one is estimating the impact of the exposure being studied.

The good news is that acute kidney injury, whether resulting from obstetric or other causes, is preventable and when diagnosed early, the condition is reversible. It also means that the county hospitals should do a better job of managing this conditions to reduce upward referrals that result in unnecessary deaths.

KIDNEY DAMAGE

There are simple tests to assess kidney damage. Kidney function is measured in terms of how efficiently kidneys filter waste from blood, a measure called the glomerular filtration rate (GFR). Healthy people commonly have GFRs of about 120. A GFR lower than 60 or another marker of kidney damage such as protein in the urine indicate acute kidney injury.

When I worked at the KNH renal unit some time back, Prof Seth Ouma Mc’Ligeyo, the head of the unit then, would always caution us about this: “When you are dealing with a patient having acute kidney injury, always assume multiple causes and look out for them”. His wise counsel has stood the test of time.

Let me begin with the obvious. A pregnant woman who is bleeding profusely can easily become hypotensive, go into shock, and injure her kidneys. The same can happen to a child or woman who has severe diarrhoea and vomiting that is not corrected urgently by replacing lost fluids. In pregnant women, uncontrolled bleeding and blood infection (sepsis) are the leading causes of preventable maternal mortality.

USEFUL CLUES

Low blood pressure following excessive blood loss can also provide useful clues. We use two measures to estimate blood pressure. Systolic blood pressure is the top number that measures pressure when the heart contracts. On the other hand, diastolic blood pressure the lower number represents pressure on the blood vessels when the heart relaxes between beats. Low blood pressure and GFR together with protein in urine could indicate problems. A renal ultrasound may be required when an obstruction such as kidney stones is suspected.

Some drugs, especially common painkillers such as aspirin and ibuprofen, and antibiotics such as gentamycin can also cause acute kidney injury. This means paying attention when taking over-the-counter drugs or asking the doctor and pharmacist. An overwhelming blood infection (sepsis) can also lead to inflammation and shutdown of the kidneys.

Experts agree that acute kidney failure is almost always accompanied by another condition. This means that patients with diabetes, high blood pressure, advanced age, or those admitted for other serious conditions should be monitored closely. Occasionally, acute kidney failure causes permanent loss of kidney function (end-stage renal disease) requiring permanent dialysis.

Subiri Obwogo is a senior quality improvement adviser at an international organisation.