Test is useful for: 

- Calculating the albumin concentration per creatinine. 

- Assessing the potential for early onset of nephropathy in diabetics using random urine specimens

What is being tested?

The Albumin/Creatinine Ratio helps identify kidney disease, a complication that arises with diabetes.

The American Diabetes Association (ADA) recommends that routine urinalysis be performed annually on adults with diabetes. 

What are the two components being tested?

This test has the two components tested. 

Albumin is a protein that is present in high concentrations in the blood. Virtually no albumin is present in the urine when the kidneys are functioning normally. Albumin may be detected even in the very early stages of kidney disease, which makes it a very reliable test.

Creatinine is normally released into urine at a constant rate and its level in the urine is an indication of the urine concentration. This allows creatinine to be measured correctly in this test.

Besides kidney disease, what else is being screened for?

The Albumin/Creatinine Ratio is used to screen people with chronic conditions such as: 

- diabetes

- high blood pressure, which puts these people at an increased risk of developing kidney disease. 

By doing this test, an individual in the very early stages of kidney disease can be identified. This is useful for the doctor or healthcare provider to adjust treatment accordingly. 

Why is that screening important?

Controlling diabetes and hypertension by maintaining tight glycemic control and reducing blood pressure helps in delaying or preventing the progression of kidney disease.

The prognostic value of consistently elevated albumin levels is particularly well established in diabetic patients.

More on proteins in plasma and urine and the kidney:

Albumin accounts for approximately 50% of the protein in plasma.

The kidney works to prevent the loss of albumin into the urine through active resorption, but a small amount of albumin can be measured in urine of individuals with normal renal function.

What is renal disease?

Renal disease is a common microvascular complication of diabetes. Without specific interventions, 80% of type I diabetics with repeatedly elevated albumin levels will go on to end-stage renal disease. Twenty percent to 40% of type II diabetics with sustained albuminuria will progress to overt nephropathy.

Note on testing intervals:

According to the American Diabetes Association and National Kidney Foundation, everyone with type 1 diabetes should get tested starting 5 years after onset of the disease and then annually, and all those with type 2 diabetes should get tested starting at the time of diagnosis and then annually. If albumin in the urine (= albuminuria) is detected, it should be confirmed by retesting twice within a 3-6 month period. People with hypertension may be tested at regular intervals, with the frequency determined by their healthcare practitioner.

More on Albuminuria:

Albuminuria, as a marker of kidney damage, provides a more specific and sensitive measurement of glomerular permeability than does proteinuria. An Albumin/Creatinine Ratio measured from a spot urine sample acquired in the early morning is preferred for initial evaluation of albuminuria. This test can also be used to confirm a positive reagent strip urinalysis result. A moderately increased Albumin/Creatinine Ratio (≥30 mg/g) for more than 3 months is diagnostic of CKD. The severity of albuminuria is also used for staging and prognosis of CKD.

Albuminuria generally appears before the reduction of glomerular filtration rate in people with diabetic glomerulosclerosis but may appear later in people with hypertensive nephrosclerosis. Albuminuria is independently associated with an increased risk of cardiovascular events and mortality. In individuals with diabetes and/or hypertension, early identification of albuminuria that prompts blood pressure and glycemic control may subsequently reduce the risk of cardiovascular events and CKD progressing to end-stage renal disease. Referral to specialist kidney care services is recommended in individuals with a consistent finding of severely increased Albumin/Creatinine Ratio (≥300 mg/g).

Factors that affect urinary Albumin/Creatinine Ratio include menstrual blood contamination, symptomatic urinary tract infections, exercise, upright posture (orthostatic proteinuria), and other conditions that increase vascular permeability (eg, septicemia). Given the pathological and physiological causes of transient albuminuria, repeating Albumin/Creatinine Ratio tests twice with early morning urine samples in the next 2 months is recommended. Albumin/Creatinine Ratio from a timed urine sample can provide a more accurate estimate of albuminuria.

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

REFERENCES:

https://pubmed.ncbi.nlm.nih.gov/7810516/

https://pubmed.ncbi.nlm.nih.gov/7708068/

https://pubmed.ncbi.nlm.nih.gov/9096972/

https://pubmed.ncbi.nlm.nih.gov/19028824/