Creatinine Levels: Impact of Exercise and Hydration

Creatinine: Differences Before and After Exercise

Hello Doctor, during the company health check, my creatinine level was found to be 1.38 mg/dL, and my glomerular filtration rate (GFR) was 63.9 mg/dL.
My cholesterol level was 205 mg/dL.
I am a carrier of hepatitis B, obese, and have mild to moderate fatty liver.
I undergo regular urine tests and liver function tests every three months, and I take 150 mg of Silymarin capsules after meals in the morning and evening.
Before I started exercising for weight loss, my creatinine and GFR were within the normal range.
After one month of regular exercise, I noticed an increase in these values, but they remain within safe limits.
Currently, I exercise for 30 to 40 minutes every morning and evening, focusing on squats, static lateral jumps (without jumping, just moving side to side), high knees with clapping under my legs, and mountain climbers.
Over the past three months, I have lost weight from 88 kg to 81 kg.
My breakfast mainly consists of two boiled eggs and a can of concentrated oatmeal, while lunch includes a large guava and a can of oatmeal drink.
For dinner, I have a normal family meal.
On the day of the health check, I exercised for 40 minutes in the morning until 6:30 AM, during which I drank about 600 cc of water.
After exercising, I urinated.
However, during the health check at 8:30 AM, I only consumed a small amount of water, about 100 to 200 cc, to retain urine for testing, and I did not urinate.
Could this be the reason for my abnormal values due to insufficient water intake after exercise? The health check facility only tested for urine pH (which was normal) and did not conduct any other tests.

kai, 30~39 year old female. Ask Date: 2020/12/21

Dr. Su Zhehong reply Internal Medicine

Intense exercise or an increase in muscle mass can cause a slight rise in creatinine levels, which does not necessarily indicate a decline in kidney function.
If the levels are not continuously rising or accompanied by proteinuria, it is generally acceptable to monitor the situation.
If there are concerns, cystatin C can be tested, as it is another marker for assessing kidney function, though it may only be available at larger hospitals.

Reply Date: 2020/12/21

More Info

Understanding creatinine levels and their implications is crucial, especially for individuals with pre-existing health conditions such as hepatitis B, obesity, and fatty liver disease. Your recent health check revealed a creatinine level of 1.38 mg/dL and a glomerular filtration rate (GFR) of 63.9 mL/min, which indicates a mild decrease in kidney function. It's important to consider various factors that could influence these results, including exercise, hydration, and dietary habits.

Firstly, exercise can have a significant impact on creatinine levels. When you engage in physical activity, especially resistance training or high-intensity workouts, your muscles produce more creatinine as a byproduct of muscle metabolism. This increase can temporarily elevate creatinine levels in the blood. However, this is generally a normal physiological response and does not necessarily indicate kidney dysfunction, especially if the levels remain within a safe range. In your case, the increase in creatinine after starting your exercise regimen could be attributed to this phenomenon.

Hydration status is another critical factor affecting creatinine levels. Dehydration can lead to a concentration of creatinine in the blood, as there is less fluid to dilute it. You mentioned that during your health check, you had only consumed a small amount of water (100-200 mL) prior to the test. This limited fluid intake could have contributed to the elevated creatinine level observed during your check-up. Adequate hydration is essential for maintaining kidney function and ensuring accurate laboratory results. It is generally recommended to stay well-hydrated, particularly before undergoing blood tests that assess kidney function.

Given your dietary habits, it appears you are making conscious efforts to maintain a healthy lifestyle. Consuming a balanced diet with adequate protein, fiber, and healthy fats is essential for overall health, particularly for individuals with liver concerns. However, it's also important to monitor your protein intake, as excessive protein can sometimes lead to increased creatinine levels, especially in individuals with compromised kidney function.

In summary, your elevated creatinine level could be influenced by several factors, including recent exercise, hydration status, and dietary habits. It is advisable to ensure you are adequately hydrated before any medical tests and to maintain a balanced diet that supports both liver and kidney health. Regular follow-ups with your healthcare provider are essential to monitor your kidney function and make any necessary adjustments to your lifestyle or treatment plan.

If you continue to notice fluctuations in your creatinine levels or experience any symptoms such as fatigue, swelling, or changes in urination, it is crucial to consult your healthcare provider for further evaluation. They may recommend additional tests to assess kidney function more comprehensively, including urine tests to check for protein or other abnormalities that could indicate kidney issues.

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