Question

What is the principle of the coulometric-amperometric method of chloride measurement?

What is microalbuminuria, what is its significance, and how is it determined?

What is the significance of an increased osmolal gap?

What is the significance of the following ratio determinations and what are their expected values? How can they be measured?

P:C (protein:creatinine)

A:C (albumin:creatinine)

Answer 1

1. Coulometric-amperometric method of chloride measurement is the most precise method for measuring chlorides over the entire range of concentrations displayed in body fluids.

Principle of the coulometric-amperometric method of chloride measurement:

This is the method using coulometric generation of silver ions (Ag+) which reacts with Cl^- to quantify the chloride concentration.

Ag²⁺ + 2Cl^- ------> AgCl₂

When all Cl^- is bound to Ag+, excess Ag+ indiacates the endpoint. A timing device records the elapsed time between the start and stop of the Ag+ generation. Beacuse the time interval is proportional to the amount of Cl^- in the sample, the concentration of Cl^- is then calculated.

2. Microalbuminuria is a condition where there is abonormal increase in Urine albumin excretion rate.

Significance: Persistent Microalbuminuria indicates the Chronic Kidney disease with high risk for cardiovascular disease.

Methods for Determination: Dipsticks or tablets that can detect microalbuminuria are available for qualitative screening of the urine.

3. Significance of an increased osmolal gap: An increase in osmolal gap with or without high- anion- gap metabolic acidosis is the important marker for exposure to one of the toxic alcohols which includes methanol, ethylene glycol, Propylene glycol, or isopropanol.

4. Significance of P:C (protein:creatinine) ratio: It is an imortant marker for determination of Proteinuria. The normal protein-to-creatinine ratio for males 18 to 83 years is <0.11 mg/mg creatinine and for females 18 to 83 years is <0.16 mg/mg creatinine.

   Significance of A:C (albumin:creatinine) ratio: It is an imortant marker for determination of Microalbuminuria. The normal value is > 30 . The value of ratio between 30-300 signifies Microalbuminuria and the value above 300 indicate that the patient is suffering from Microalbuminuria.