Generally speaking the answer is, no. There is no change or worsening of kidney function, blood concentration, and electrolyte imbalances. The body has strange ways to deal with excessive sweating. In my own experience over the years of seeing thousands of people suffering from hyperhidrosis I did not see any cases that had renal (kidney) function problems or anything related to dehydration.
Another common question asked relating to this is the relationship between hormonal problems and hyperhidrosis. In the aging population, especially among women there are a lot of complaints about facial / hair excessive sweating that comes especially after menopause. We know that menopause carries with it some hormonal changes which can cause this specific type of sweating but the exact cause is unknown as of yet. Also the treatment for this type of sweating in the elderly popular is NOT a surgical one.