Authors: Dr Colin Michie, Paediatrician; Dr Stephen Hyer, Physician
By 2030, dialysis will have to be provided globally to twice as many patients as at present. Fewer than half of those requiring this treatment can access it now. As access is often compromised by environmental disasters, we therefore all need to think about the health of our kidneys!
Again, globally, dialysis consumes an estimated 1.56 billion litres of water, 1.62 billion kilowatt hours annually, about the same as a small city, generating over 600,000 tons of plastic waste.
More efficient, smaller, home-based systems are desperately needed, particularly for those living in Antillean countries. We should all make a stir about this; dialysis has hardly changed since its early invention by a Dutch doctor in the 1940s.
Additionally, we must encourage more kidney donations for transplantation, particularly within families. The supply of donor organs is never sufficient for the growing demand. Giving a kidney to save someone’s life is a wonderful act.
Unsung heroes that keep you running smoothly – your kidneys
“We who are born of the ocean,” wrote Kamau Brathwaite. Even on Soualiga, our bodies are mostly water. But the fluids inside all human cells are salty, as is our blood, with similar sodium levels as the sea. Careful salt balance is required, irrespective of how much fluid we lose to the sun, or how much we drink.
For tiny plankton in the tropical seawater of Simpson Bay, this is not difficult – some molecular pumps or transporters in their membranes exchange sodium, water (called aquaporins) and a few other useful atoms such as potassium, calcium and magnesium. Humans with our many trillions of cells use kidneys to perform these same functions.
Kidneys perform many “total organism” jobs. They remove nitrogenous waste from protein turnover as urea or uric acid. This requires water, so kidneys know your blood volume and control your blood pressure together with your heart. Kidneys balance calcium and phosphate and make vitamin D: they are crucial to bone and muscle development and strength.
Kidneys remove compounds such as toxins and drugs. Together with your lungs, they ensure blood does not become too acid or alkaline, even when you run, or hyperventilate, or forget to drink for a day. Your “rinones” keep you healthy, adaptable and resilient.
An amazing filtration system
The kidneys filter blood flow from the aorta through two big arteries: about 1-2 litres per minute at rest. They use more blood flow than your brain, even when you are thinking hard! Their filtration keeps nutrients and proteins in the blood, while producing 1-1.5 litres of urine a day.
They do this with a deep, thick forest of fine tubules, each of which is fed by a cup-like glomerulus in which tiny tufts of blood vessels produce fluid that is filtered through the tubules.
We have between 300,000 and a million glomeruli in each kidney. No proteins or red cells find their way into the urine. Such high-fidelity filtration needs lots of oxygen. It is sensitive to toxins – smoking tobacco; drugs of abuse, such as ecstasy and amphetamines; environmental toxins, such as mercury or arsenic can all damage the lattice of glomeruli and tubules.
Kidneys are wonderful organs but have built-in obsolescence. You can measure their efficiency by looking at the amount of blood filtered – their glomerular filtration rate. Our glomerular filtration rate falls steadily as we become older. This starts once you are over 40 years old, caused by the steady decrease in the blood flow to the glomeruli.
What happens if your kidneys do not work well?
The glomerular filtration rate (or GFR) should be 90-140 in a healthy adult. This figure is lower in women. The units of the measurement are millilitres per minute – the blood volume the kidney glomeruli work on. Kidney failure can be rapid – acute kidney failure. This can happen if you lose a large amount of blood, for instance, or some infections. Slow deterioration causes chronic kidney disease (CKD). Failure is classified by the GFR.
You may feel perfectly well until your GFR falls below 15, when waste products such as urea and phosphate start to accumulate, along with fluid, causing abnormal salt levels. This causes drowsiness. If the GFR drops below 10, you will probably require support with dialysis. Faults in kidney filtration lead to proteins or red cells leaking from blood into the urine, measured using a test strip dipped into a urine sample.
Kidney performance can be checked by measuring your blood pressure. High pressures develop as the kidneys try to increase their blood supply. Raised pressures cause more work for the heart and damages blood vessels, leading to infarctions, strokes or aneurism. Kidneys may be checked with specialised imaging or biopsies too.
Why is chronic kidney disease on the increase?
Chronic kidney disease (CKD) affects about 10% of us and has been increasing steadily. The greater age of many populations and the epidemic of obesity, linked to diabetes and high blood pressure are the cause.
Chronic kidney disease is also more likely to develop in those who have suffered with kidney stones and those who have suffered recurrent dehydration. On St. Martin, lupus also damages kidneys. Chronic kidney failure is deadly. It causes enormous ethical challenges and cost to patients, families and communities.
CKD has to be treated by regular dialysis or, if possible, transplantation from a suitable donor. At present, a substantial amount of dialysis is delivered by putting fluid into the abdominal cavity (peritoneal dialysis) rather than using filters connected to blood vessels (haemodialysis).
At the level of national healthcare systems, there is frequently a shortage of dialysis. Technological ingenuity has yet to scale up suitable replacements for our multipurpose kidneys. There are never sufficient donor kidneys for transplantation.
Can you keep your kidneys healthy?
We all need to reduce the workload on our kidneys by exercising regularly. This preserves their blood flow and improves your fitness. Try to avoid excessive use of common painkillers such as paracetamol and aspirin. Only take these when you need them. Long term analgesic use can damage kidneys.
Your diet should be rich in fruit and vegetables, low in salt – so watch the hot sauces, breads and cheeses, all of which are usually high in salt. You need to pass about two litres of urine a day. Using more plant proteins will keep cholesterol and lipids healthy. If you suffer with diabetes or raised blood pressure, be careful to take prescription medications regularly to protect those glomeruli and tubules.
It is true that a number of bush teas can be of benefit to your blood pressure and blood sugar levels, but studies in the Caribbean have shown them to be less effective than those pills. Your kidneys are not worth risking! Seek specific dietetic advice if you suffer with kidney stones.
No specific herbal treatments have been found to reverse declines in kidney function. Some useful summaries of this can be found at https://www.cdc.gov/kidneydisease/index.html. Stopping tobacco smoking (as always) is a good idea, as this improves kidney circulation. Perhaps COVID-19 helped you stop anyway, but here is another good long-term reason to do so!
So where does this leave us in St. Martin in 2020?
At this time of the COVID-19 pandemic, we could all reflect on how we plan our lifestyles around these silent, precious organs! Try drinking two soothing litres of water a day. Your kidneys will do better for it.