Incomplete distal renal-tubular acidosis (i-dRTA)

A group of disorders in which the excretion of hydrogen ions (H⁺) and/or the reabsorption of bicarbonate (HCO^3-) in the kidneys is impaired, are identified as renal-tubular acidoses.

The mentioned disease i-dRTA can be inherited or later on in the life be acquired. The urine shows an abnormal acidic value, do to a underexcretion of hydrogen ions (pH > 5.5). To compensate for this negative effect, the organism uses the blood buffer system, i.e. by shifting electrolytes between blood and urine. The chronic process is associated frequently with complications of kidney calcification or a formation of kidney stones. Furthermore, the bone microarchitecture is deteriorated in the long term due to the net loss of calcium. It is known from the literature that a reasonable proportion of patients with kidney stones or osteoporosis have this underlying disease.

Chronic kidney disease with metabolic acidosis

Disorders of the renal function and/or pathological changes in the renal structure are triggers of a renal failure. The capacity of the kidneys to excrete urophanic metabolic substances decreases. The more advanced the disease symptoms are, the higher is the incapability to keep the acid-base balance in the blood. So a renal failure affects primarily the acidity regulation. That’s the starting point for the development of a metabolic acidosis in connection with a renal impairment. The bicarbonate buffer system will change towards a deficit.

The incidence of the metabolic acidosis increases proportionally according to the degree of the renal failure and with the decrease of the renal function respectively.

This kind of acidosis connected with a chronic kidney disease (CKD, stage 2 to 4) must be treated as early as possible and for a long time. This will contribute to the recovery of the renal function and restore the homeostasis. The latter must be sought in view of the proven long-term complications of metabolic acidosis: e.g. impairment of the muscle metabolism, decrease of the bone mineral density, decrease of the insulin effectiveness, and reduction of the cardiac function.

Chronic metabolic acidosis

A well-functioning buffer system guarantees that the concentration of acids and bases in the body is well balanced and therefore all biological and physiological processes in the body perform at their best. The buffer system is regulated by the kidneys’ filtration and excretion and ensures that the blood pH value ranges between 7.35 and 7.45.

The lifestyle is crucial. An unbalanced diet, e.g. excessive consumption of animal proteins and various genetic or acquired diseases can adversely disrupt this buffering system and thus facilitate metabolic acidosis. However, this does not produce any immediate symptoms. But if this condition remains unchanged over a longer period of time, various complications or secondary organic lesions can occur.

One of the long-term symptoms is the loss of bone substance, that will result finally in an osteopenia and osteoporosis. This also amplify the age-related decrease of the kidney function. The effectiveness of insulin will be reduced, which can promote the beginning of a diabetes mellitus. A further possible complication is be the formation of kidney stones.

Prevention of secondary kidney stones

The development of kidney stones (Nephrolithiasis) is a widespread disease, associated with painful episodes, hospitalizations and, not neglectable, surgical interventions. The causes of stone formation are low fluid intake, too few vegetables and fruits (citrates), too much oxalate and animal proteins and excessive salt intake. All of these boosters should be counteracted so that the mineral concentrations in the urine can be reduced and any crystallization prevented.

Approximately 80–90% of the kidney stones contain calcium in different salt forms. The increased urinary excretion of calcium, oxalate and low citrate are the most striking features of these patients. Kidney stones occur more frequent in western countries. The recurrence rates after the first episode of stone formation increase strongly from 40% within the first 5 years to 50% within 10 years and over 75% within 20 years. Therefore it is very important to prevent these relapses, because each episode of a stone formation is harmful to the kidneys.

Disturbed glucose tolerance

The measurement of the blood sugar concentration serves as a simple parameter for the diagnosis and differentiation of the various disorders of the blood sugar level up to diabetes mellitus. The disturbed glucose tolerance is evident from a slightly pathological fasting glycaemia. However, the oral glucose tolerance test shows abnormal values. Impaired glucose tolerance is likely to be widespread in the Western population. In particular, patients with a metabolic syndrome from a complex of abdominal obesity, hypertriglyceridemia, arterial hypertension an impaired carbohydrate metabolism are exposed to this risk. Dysfunctional glucose tolerance is quite manifold in terms of negative effects. Well known are e.g. changes in insulin homeostasis and insulin effectiveness or a perturbed acid-base buffer system with acid overload.