【BUN & CREATININE Renal Function】

Normal Creatinine Levels

Normal creatinine levels range from 0.8 to 1.4 mg/dL (milligrams per deciliter), according to the NIH - National Institutes of Health. Lab professionals check levels of this substance by drawing a sample of blood from one of the veins in the body. This test has few risks and helps doctors determine if a patient needs additional tests.

 

What Can Cause Elevated Creatinine?

 

So, what can cause elevated creatinine in a human?

Kidney disorders often result in higher-than-normal creatinine levels. The kidneys filter wastes from the blood, so when kidney damage occurs, creatinine and other waste products build up in the body. Examples of kidney disorders that lead to high creatinine levels include

acute tubular necrosis,

glomerulonephritis,

kidney failure, pyelonephritis (kidney infection) and

reduced blood flow to the kidneys.

 

Other conditions also lead to high levels of creatinine in the blood.

Dehydration,

shock, and

congestive heart failure reduce the amount of blood flow to the kidneys and prevent these important organs from carrying out their functions. Examples of other conditions leading to elevated serum creatinine include

diabetic neuropathy,

rhabdomyolysis,

muscular dystrophy,

preeclampsia, and

eclampsia.

weight gain,

high cortisol,

low thyroid,

higher muscle mass,

dehydration, and a

lack of sleep can also increase creatinine.

How does creatinine and urea levels increase?

Creatinine is the by-products of muscle metabolism and urea forms after protein breaks down in the body. Both of them are discharged by the kidneys as a kind of waste. Since they produce at a relatively stable rate, the elevation of creatinine and urea always associated with kidney damage.

Therefore, high creatinine and high urea occur at the same time.

 

Is it normal with high creatinine but normal urea levels?

Even though this condition is not so common, it is normal for you to to experience this condition.

This result is usually due to muscle breakdown which would release more creatinine into blood. Exercise may produce such an increase. Pathologic muscle breakdown would produce sharp levels, but such states would likely be accompanied by symptoms of weakness in particular.

 

If you have hi-muscle-mass then your high creatinine level might be normal for you. There is also a possibility of error on the laboratory which would be the most suspect for borderline cases. Some reports even say that weight gain, high cortisol, low thyroid, higher muscle mass, dehydration, and a lack of sleep can also increase creatinine.

 

Symptoms of too much creatinine

Some people find out they have kidney failure when extreme creatinine amounts show up in routine blood tests, without feeling any symptoms at all. Yet some people may experience the following:

• Weakness, or feeling tired
• Dehydration
• Confusion
• Shortness of breath

 

Creatinine clearance (Ccr or CrCl) measures how much creatinine is cleared out of the body, or how well kidneys filter waste.

Creatinine clearance is a combination of a urine and blood test.

A creatinine clearance test is usually ordered if the serum creatinine level is higher than normal or when a person is starting dialysis. Normal creatinine clearance for men is between 97 to 137 milliliters per minute, and women have a normal clearance of 88 to 128 milliliters per minute.

BUN/creatinineis the ratio between blood urea nitrogen (BUN), a waste product in the blood from protein metabolism, and creatinine. 

If both BUN and creatinine are high, the ratio usually indicates damage to the kidneys.

If BUN is high but creatinine is normal, then the kidney is generally not damaged but is not getting adequate blood supply due to another problem such as dehydration or heart failure.

If creatinine is high but BUN is normal, maybe due to Rhabodymolisis, hypothiroidism, 

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BUN is normal and creatinine level was 7.6

when i was admitted to the hospital.  I was hospitalized one week prior with Rhabodymolisis. 

 

Case Report

 

A 30-year-old male presented with a history of generalized edema and significant weight gain of 20 kg in 6 months. He had tiredness, significant myalgia, and slurring of speech. The creatinine was elevated at 2.12 mg/dL, which was the reason for referral to the nephrologist. Routine investigations revealed a completely normal hemogram and urine analysis, elevated creatinine at 2.17 mg/dL but normal blood urea at 15 mg/dL. Hypothyroidism was suspected, which was confirmed with a T3 of 0.19 ng/mL, T4 of 0.4 μg/mL, and a thyroid stimulating hormone (TSH) of 780 μIU/mL. Creatinine kinase / or creatine kinase (CK) was 11,365 U/L. He also had abnormal lipid profile and abnormal liver enzymes. Abdominal ultrasound showed completely normal kidneys and mild fatty changes in the liver. Echocardiography was normal. A diagnosis of severe hypothyroidism with myopathy was made and given the normal blood urea, normal urine analysis, and renal ultrasound, the raised creatinine was thought to be secondary to excessive production rather than impaired renal function. He was commenced on thyroxine replacement therapy and a review in 2 weeks revealed a CK of 2,228 U/L and a creatinine of 1.5 mg/dL, both of which had normalized during the subsequent visit.

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An elevation in the serum creatinine concentration usually means a reduction in the glomerular filtration rate (GFR), and is associated with a concomitant rise in the blood urea.

However, there are a variety of settings in which the creatinine can increase in isolation, independent of the GFR, and therefore there is no true change in the overall kidney function.

This may be due to one of the three factors:

Decreased creatinine secretion,

interference with the serum assay, or

enhanced creatinine production.

Our case is one such example of a mechanism where there is likely to be a release of pre-formed creatinine from injured muscle and/or release of creatine that is then converted into creatinine in the extracellular fluid. It is important to look for such unusual causes in someone with unexplained isolated elevation in serum creatinine, especially in the absence of other markers of renal disease like abnormal urine analysis or ultrasonological abnormality of the kidneys.

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To conclude, our patient had an unusually high level of CK, which resulted in elevation in his serum creatinine level, both of which normalized with the treatment of hypothyroidism. Elevation in serum creatinine levels can occur even in the absence of decline in the GFR, and one should look hard for unusual causes, especially in a patient with absence of concomitant elevation of blood urea.

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Serum creatine kinase levels (CK) can vary among healthy subjects, even when correcting for muscle mass. Age, gender, race, and physical activity can affect CK. CK is higher among black males, as well as newborns.^[1] Moreover, CK reference ranges are varied with different assays and reference temperatures. According to the International Federation of Clinical Chemistry (IFCC), the upper reference limit of CK in adults is determined by the 97.5^th percentile at the standard temperature of 37^o C (as seen in the table below).^[2]

Table 1: The Adult 97.5^th Percentile Cutoff Values for Serum Creatine Kinase(Open Table in a new window)

Gender	Conventional Units (U/L)	SI Units (mkat/L)
Male	171	2.86
Female	145	2.42

 

In the European Society of Cardiology (ESC) and American College of Cardiology Consensus recommendations, a cutoff value of the 99^th percentile reference limits of CK-MB is used to determine myocardial infarction.^[3] However, the reference range for serum CK-MB in adults is also varied among laboratory assays as shown in the table below.^[4]

Table 2: The Adult 99^th Percentile Cutoff Values for CK-MB in Different Manufacturer Assays (Open Table in a new window)

Manufacturer Instrument	Male (µg/L)	Female (µg/L)
Abbott: AxSYM	8.7	4.8
Beckman: Access	8.2	5.6
Ortho-Clinical Diagnostics: Vitros ECi	4.21	2.95
Dade-Behring: Dimension RxL	4.2	3.1
Bayer: Centaur	4.38	1.68
Roche	7.6	4.66
Tosoh: AIA	5.6	3.6

 

 

 

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