Q: Is a high protein diet bad for your kidneys?
A: Renal metabolism is a matter of hydration, sodium intake, systemic blood pressure (BP) and nitrogen balance of course.
Red meat tends to elevate serum creatinine.
The reason is, that it is high in creatine, metabolized to creatinine.
However if kidneys are well hydrated and under normal BP, 5gr of creatine mono hydrate are well tolerated.
High BMI >30 will have an impact on creatinine.
The reason is muscles are plenty in creatine.
That eventually will also be metabolized to creatinine.
Moreover, under rupture muscles release myoglobin, the protein carrier of O2 to skeletal muscles.
That can increase creatinine under overtraining and rhabdomyolysis.
Myoglobin is toxic to renal glomerulus.
More muscle tissue, equals more creatine kinase (CK) elevation under training.
This is why the GFR formula doesn’t apply for bodybuilders; but for sedentary individuals with a casual physical activity schedule.
Serum creatinine and GFR are reversely related.
Excessive animal protein intake along with dehydration, can lead to azotemia
Meaning elevated serum urea.
In urea’s cycle, ammonia (NH3) is a toxic byproduct.
Occasionally there’s odor of NH3 in the sweat or the skin of bodybuilders who are under diet and consume >3gr/kg of protein.
This can give a lethargic foggy mind.
Resembling the hepatic comatose state.
Drugs like non-steroidal anti-inflammatory drugs (NSAIDs) and certain antibiotics can elevate creatinine.
So does AAS that kick BP and harden the renal glomerulus.
Trenbolone is an example.
Focal Segmental Glomerulus Sclerosis is the result of this.
That leads to protein wasting, known as proteinuria.
Normally there is just protein traces in urine.
Marathon running can cause proteinuria out of the thousands of steps that lead to concussion of kidneys.
Under microscope assessment we can see cylinders, which form within the renal tubules.