What is Distal Renal Tubular Acidosis?
Distal renal tubular acidosis (dRTA) is a rare condition which affects approximately 1 in every 100,000 people worldwide. It is caused by a build up of acid in the body as a result of malfunctioning kidneys. High levels of acid can cause rickets and kidney stones in addition to other complications. When patients experience recurrent kidney stones, Chronic kidney disease (CKD) can develop.
Most people inherit dRTA as a result of a gene mutation. However, because the specific gene that is mutated varies among patients, everyone experiences the disease in a slightly different way. Some are even asymptomatic. There are six gene mutations currently identified which can cause dRTA.
Symptoms of dRTA can include fatigue, thirst, large amounts of urine, growth disorders, deafness (in some forms of the condition), bone damage, and a deficiency of serum potassium. This deficiency in particular can cause cardiac arrhythmia, paralysis, and early death.
Fortunately, there is an effective treatment for this disease. Patients are prescribed alkali supplements which they must take daily for their entire lives. These help the body retain kidney function. They are also marked with improvements in patient growth rates.
Although yes, there is a known effective treatment for dRTA, researchers know there is a severe lack in communication between countries concerning this disease. Without collaboration, there was no way to know if all patients were receiving adequate care. Likewise, there was a lack of data regarding the efficacy of treatment for patients worldwide.
Partly, this is simply because the disease is rare. There have been no long-term investigations of dRTA’s progression or prognosis utilizing a large, worldwide patient sample. This lack of data not only makes the condition difficult to manage, it impedes physicians ability to fully inform patients and their families about their prognosis.
To combat this issue, a group of prestigious research associations came together to conduct a multinational study. The European Renal Association- European Dialysis and Transplant Association (ERA-EDTA), the European Reference Network for Rare Kidney Diseases (ERKNet), and the European Society for Paediatric Nephrology (ESPN) were involved. The ultimate goal? To solve unresolved questions in this disease, improve diagnosis, treatment, and care for those living with it, and examine the handling of dRTA among physicians and patient families.
In total, this trial included 340 patients who spanned 29 countries. All patient data (genetic, biochemical, clinical, and demographic) were collected by online forms. 52% of participants were female and 48% were male. It included both pediatric and adult patients from age 0 to 70 with a mean participant age of 11 years. 83% of patients were 18 years of age or older.
Presentation of the illness occurred between the ages of 0 and 54 with a median age of 6 months. Gene mutation analyses were conducted for 206 of the participants, resulting in mutation identification in 170 individuals.
- Stage 2-4 CKD: 82% of adults, 35% of children
- Stage 5 CKD: 0%
- Nephrocacinosis: 88% of all patients
- Slightly below average heights for adults
- Hearing loss: 36% of all patients (most frequently in those who had mutations in ATP6V1B1)
- Kidney stones: 21% of all patients (42% of those with mutations in SLC4A1)
- Adequate therapy was received by only 158 patients, or 51%
These results are unarguably mostly positive in terms of patient outcomes. However, it is extremely important to note two things. One, that those who had the best outcomes with this diagnosis were the ones who received treatment and two, that those who received treatment were primarily from countries with a high GDP. This shows a disconnect in care and wellbeing among dRTA patients among different countries.
In some ways, the basic results from this study are common sense. Treatment improves outcomes for patients. For dRTA specifically, this means proper growth and improved kidney function. However, it is striking to see the variation in outcomes among countries. Hopefully, these results will provide a reality check on the importance of proper treatment for this condition. With support from the international nephrology community, we will hopefully be able to establish better management of distal renal tubular acidosis across all countries for all patients living with this rare disease.
You can read more about this multinational study here.