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Clinical Diagnosis of Stages of Chronic Kidney Disease

Clinical Diagnosis of Stages of Chronic Kidney Disease
Stages of chronic kidney disease. This is defined by the National Kidney Foundation and Kidney Disease Outcomes Quality initiative published in 2003. So based on GFR in milliliter per minute per 1.73 meters square. There are four stages and five RIFLE of kidney disease. The normal is greater than or equal to ninety. Mild is sixty to eighty nine. Moderate is thirty to fifty nine. Severe is fifteen to twenty nine. And it’s considered kidney failure if the GFR is less than fifteen. These clearance values are based on milliliter per minute for one point seven meters square. And therefore, the calculated are derived from the MDRD formula. For clinical diagnosis, normal kidney function Is defined as estimated GFR greater than sixty.
Again normalized to one point seven three meters square. And Cystatin less than 1.0. For preclinical kidney disease. Estimated GFR is greater than sixty and the Cystatin C greater than 1.0. And for chronic kidney disease, estimated GFR less than sixty and Cystatin C greater than 1.0. So this is for the purpose of clinical diagnosis. We have been talking about creatinine clearance or renal excretion of creatinine. Now we are going to shift a little bit to talk about drug excretion by the kidneys or renal drug excretion. Renal excretion refers specifically to the amount of drug excreted unchanged in a urine per unit time. Therefore, the unit is for example milligram per hour.
Inactive metabolite is considered cleared although it is physically reside still in the body system. However, active metabolite is considered a drug.
There are several synonyms: unchanged drug, parent drug , intact drug, unmetabolized drug. They all refer to the same thing. The unchanged drug itself. Renal drug clearance.
Definition: Renal clearance of the drug is the volume of plasma water that is clear of the unchanged drug per unit time by the kidneys. By the same token, renal clearance of the metabolites is the volume of plasma water that is cleared of the active metabolite per unit time. These two clearance terms should not be confused with each other because they are not the same. And the unit for clearance is expressed as milliliter per minute. Or normalized to body weight milliliter per minute per kilo. or normalized to body surface area milliliter per minute per 1.73 meters square.

In this step, Prof. Lee illustrates the different stages of Chronic Kidney Disease based on GFR in mL/min/1.73m2 .

In clinical situation, we will consider Cystatin-C as well.

When estimated GFR > 60 ml/min/1.73 m2 and Cystatin C < 1.0 mg/L, we will consider it as normal kidney function.

When estimated GFR > 60 ml/min/1.73 m2 and Cystatin C > 1.0 mg/L, we will consider it as pre-clinical kidney disease.

When estimated GFR < 60 ml/min/1.73 m2 and Cystatin C > 1.0 mg/L, we will consider it as chronic kidney disease.

Besides, Prof. Lee explains the renal drug excretion and renal drug clearance.

Could you distinguish the difference between the renal clearance of the drug and the metabolite? Please leave your answer below.

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Pharmacokinetics: Drug Dosing in Renal Disease

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