Renal calculations
Kidney stones – identified by the medical term "nephrolithiasis" or "renal lithiasis" – are small aggregations of mineral salts that form in the urinary tract. Often their presence is linked to an incongruous diet with which a underlying genetic predisposition is necessarily associated. Sometimes kidney stones are asymptomatic and are discovered by chance during a control X-ray. At other times, acute and violent pain (renal colitis) strongly signals their presence.
WHAT ARE RENAL CALCULATIONS?
Renal stones are deposits of hard consistency formed by precipitation of the mineral salts contained in the urine (calcium, oxalate, phosphates and uric acid).
The formation of a calculation is facilitated by an increase in the concentration of these electrolytes or by a reduction in the liquid holding them in solution (low urine volume).
When the salts aggregate together they form crystals first, then microcalcules and finally calculations that can reach the size of a golf ball.
Precisely because of their chemical shape and composition, kidney stones can move from the original site and go to hinder the flow of urine. This obstacle, in addition to causing often intense pain, promotes the development of urinary infections and, if it persists for long periods, increases the chances of damage to the kidneys,to develop progressive renal failure.
Urines normally contain substances that prevent the formation of calculations, but these compounds are not always present in adequate quantities or effectively perform their function. Today two categories are known: macromolecular (protein) and micromolecular such as citrate or magnesium.
Mucopolysaccharides, thanks to their colloidal properties, also promote the maintenance of salts in solution by removing the formation of kidney stones.
Based on chemical composition different types of calculations are distinguished, each requiring a different therapeutic approach:
RENAL CALCULATIONS, ORIGIN, ACCIDENT AND CLASSIFICATION: |
||||
|
CALCICA (70-80%) |
MISTA (5-10%) |
HURRY (5-15%) |
INFECTIVE (10-15%) |
CHRISTICAL (1-2%) |
|
Calcium oxalate (60%)
Calcium oxalate and calcium phosphate (30%)
Calcium phosphate (10%) |
Calcium oxalate, uric acid and calcium phosphate (30%) | Uric acid, calcium urate |
Struvite (phosphate – ammonium – magnesium)
Struvite and apatite carbonate or ammonium urate
Calcium phosphate |
Cystine |
|
To these data should be added the calculations of rare origin (incidence 1-2 %) that can be caused by the accumulation of xanthine, hypoxanthin, cholesterol, fatty acids or 2.8-hydroxyadenine |
||||
Risk factors
Kidney stones are quite common in the population as they affect on average about 3% of people. Males aged 20 to 40 years are particularly at risk. In this age group, due to the simultaneous presence of several risk factors, the incidence of the disease exceeds 15%.
The source causes of the calculation have not yet been fully clarified, although some predisposing factors significantly increase the probability of calculations forming:
- gender: males have a triple probability compared to women to develop urinary tract calculus (the higher concentration of citrate in female urine, in close relationship with estrogenic rate, would explain this lower incidence of the problem in the gentle sex)
- little liquid intake: a limited urine flow favours stagnation, therefore precipitation of the salts contained in them
- dehydration due to increased fluid loss (diarrhoea, hyperhidrosis, etc.
- age: kidney stones are mainly formed between twenty and forty years
- urine acidity: urinary pH less than 5 (as regards some well-defined types of calcium, such as cystine, xanthine and uric acid)
- Family history of kidney stones: is the case for example of cystic calculations in which, due to a congenital kidney defect, a poorly soluble amino acid in urine (cystine) precipitates forming crystals
- chronic urinary tract infections
abuse of certain medicines or saline and vitamin supplements - hyperthyroidism (catabolic effect on bone tissue) and hyperparathyriodism (calcaemia increased)
Incongruous diet - ethnicity: increased incidence of kidney stones in the white and Asian race
- climate (during the hot summer period, the greater evaporation, if not replenished by adequate fluid supply increases urine concentration and precipitation of the calculations)
