Professor of Dermatology
B’ Vice President GDHI
President Hellenic Academy of Thermal Medicine
President World Academy of Chinese & Complimentary Medicine
External hydrotherapy, as a form of Thermal Medicine, consists of body immersions in thermal water a process that affects blood flow to the kidneys and renal regulatory systems in many ways, since blood flow to the kidneys increases immediately after immersion, causing an increase in creatinine clearance and sodium and potassium excretion.
The increase in sodium excretion is time-dependent and increases as a function of water depth, due to the displacement of the increased intravascular plasma volume. During body immersion, the plasma volume initially increases, as the pressure in the immersed tissues increases above the capillary pressure, favoring capillary absorption. Fluid displacement comes from the intracellular space, and the role of kidneys, in short immersion, is to minimize the increase in plasma volume that would, otherwise, lead to a much greater increase in cardiac output.
Renal function is further regulated to a large extent by renin, aldosterone and antidiuretic hormone, which are significantly affected by immersion of the body in water, such as angiotensin-stimulating renin, which in turn stimulates aldosterone release. However, renin activity decreases with time-dependent immersion, from minutes to hours in water, while diuretic and natriuretic responses occur after 40 minutes of immersion in the body. The combination of the effects of immersion, on both urinary and sympathetic nervous system, leads to a reduction in blood pressure in prolonged immersion for a certain period of time.
Positherapy, a form of internal hydrotherapy, is a complementary form of treatment that includes the consumption of a certain amount of thermal water at the place of production, which can have a beneficial effect on various diseases of the urinary system. Positherapy causes a significant increase in the pH of the urine and, in fact, at levels that are considered a deterrent to the regeneration of Ca2+ oxalate stones. Futhermore, positherapy increases the concentration of lithogenesis inhibitors, such as Mg2+ and citrates, while urinary oversaturation of Ca2+ oxalate decreases significantly, as well as, uric acid precipitation.
Positherapy is the cornerstone in preventing and reducing recurrences of urinary lithiasis, which is an important clinical entity with difficult, often, definitive treatment. Thermal water has a prophylactic effect against lithiasis, on one hand, by increasing the volume of urine and the excretion of lithogenesis inhibitors and, on the other hand, by reducing the oversaturation of lithiasis crystals in the urine.