Urolithiasis – (Kidney stones / Urinary stones / Bladder stones)

All information on urolithiasis – (Kidney stones / Urinary stones / Bladder stones)

At a glance

Urolithiasis refers to the formation or occurrence of concrements (urinary stones) in the urinary tract. For example, in the renal pelvis or in the bladder

Urolithiasis can be divided into:

  • Nephrolithiasis: Stone in the hollow system of the kidney (kidney stone)
  • Ureterolithiasis: Stone in the ureter (ureter stone)
  • Cystolithiasis: Stone in the bladder (bladder stone)
  • Urethralithiasis: Stone in the urethra
For more information

About 5-10% of all people form stones during their lifetime. The ratio between men and women is about 3:1. Stones also appear more frequently in old age (age peaks 40 to 50 years of age) and are rather rare in children (1-5% of the stone patients).

More than 80% of the urinary stones consist of calcium salts (calcium oxalate or calcium phosphate). While in Western countries infection-associated stones decrease due to increasing prophylaxis (magnesium ammonium sulfate/carbonapatite), uric acid stones increase in frequency.

Causes:

  • Over- and malnutrition
  • Inheritance
  • Exsikcosis (dehydration)
  • Lack of exercise
  • Idiopathic (without discernible cause)
  • Anatomical abnormalities of the urinary tract
  • Metabolic defects (renal tubular acidosis)
  • Drug-induced (calcium, vitamin D, >vitamin C 4 g/day)

With increasing concentration of dissolved substances, crystal and stone formation occur in the urine. Also Kidney healthy excrete crystals daily due to urinary oversaturation. However, there are different crystal excretion patterns in healthy and stone-formers. Healthy ones excrete small crystals (5<microns), stone-forming crystals and crystal conglomerates up to 300 microns.

Inhibitors that prevent the crystallization of most stones are:

  • Magnesium
  • Citrate
  • Biphosphate
  • Polyanions
  • Glycoproteins

Promoters that promote crystallization are:

  • Oxalate
  • Calcium
  • foreign surfaces
  • Urothellaesions

Types of stone:

  • Calcium Oxalate Stones: (CaOx) 80-90% of all urinary stones
  • Uric acid stones: about 8-10% of all urinary stones
  • Infectious stones/ struvit stones: about 5-7% of all urinary stones
  • Calcium phosphate stones: about 4-6% of all urinary stones
  • Cystine stones: about 0.5-1% of all urinary stones

 

Uric acid stones are often the result of unbalanced diet and lack of exercise. Uric acid is extremely poorly<soluble in the acidic pH range ( <6), the most common cause of uric acid stones is not hyperuricosuria, but acidic urine (so-called “acid rigidity” of the urine, i.e. pH value in the course of the day always under pH6). Increased uric acid excretion takes place, among other things, in gout.

In contrast to uric acid stones, calcium phosphate stones are favored by high urine pH values. They are often mixed stones with calcium oxalate or struvit stones (in renal tubular acidosis and infections).

 

Diagnosis

Urine test strips can be used to verify, among other things, the specific weight and hematuria. Different crystals can be made visible in the urine sediment. In the collective urine, lithogenic substances (calcium, uric acid, oxalate, phosphate, cystine, dihydroxyadenine (DHA)) can be quantified. Previous stones can be examined by infrared spectroscopy. In addition, various imaging methods are suitable for stone localisiation.

 

Prophylaxis:

  • Nutrition with little animal proteins and little salt
  • Drink a lot
  • Avoid drinks and food that acidify the urine (e.g. apple juice, beer)
  • Lose weight in case of obesity

Sources

  • Schmelz, H.U. et al.: Facharztwissen Urologie , 2. Auflage, 171-196
  • Hesse, A. et al (2003): Study on the prevalence and incidence of urolithiasis in Germany comparing the years 1979 vs. 2000. Eur Urol , 709-713
  • Hesse, A. et al (2009): Urinary stones: Diagnosis, treatment, and prevention of recurrence. Karger, Basel
  • Siener, R., Hesse, A. (2003): Fluid intake and epidemiology of urolithiasis. Eur J Clin Nutr 57 (Suppl 2), 47-S51
  • Holmes, R.P. et al. (2001): Contribution of dietary oxalate to urinary oxalate excretion. Kidney Int 59, 270-276
  • Deutsche Gesellschaft für Ernährung, Österreichische Gesellschaft für Ernährung, Schweizerische Gesellschaft für Ernährungsforschung, Schweizerische Vereinigung für Ernährung (D-A-CH) (2000): Referenzwerte für die Nährstoffzufuhr. Umschau Braus, Frankfurt a. M.
  • Buclin, T. et al (2001): Diet acids and alkalis influence calcium retention in bone. Osteoporosis Int 12, 493-499
  • Siener, R. et al (2004): The role of overweight and obesity in calcium oxalate stone formation. Obes Res 12, 106-113
  • Schroeder, U. et al. (02/2017):Übersäuerung – basische Ernährung– Entschlackung, Tritime Magazine
  • Hubert, M. (2015):Gicht – Hohe Harnsäurewerte treiben die Kosten hoch, Springer Medicine, URL: https://paperity.org/p/73752731/gicht-hohe-harnsaurewerte-treiben-die-kosten-hoch, Retrieved 18.06.2019
Status of information: Autumn 2019