DIAGNOSTIC REAGENTS 327 



BAGTO-THYMOL TURBIDITY REAGENT (B328) 



Bacto-Thymol Turbidity Reagent is recommended for use in the Maclagan 

 thymol turbidity test and its modifications for indicating hepatic parenchymal 

 impairment. It is a barbital buffered saturated thymol solution with a reaction of 

 pH 7.55, prepared according to the method described by Maclagan,^ and the 

 modification of Mateer et al.^-^ 



It was observed by Maclagan,^ that a turbidity or precipitate formed in a 

 buffered saturated thymol solution when serum from patients with certain types 

 of liver disease was added to it. The degree of turbidity paralleled closely the 

 severity of parenchymatous hepatic impairment and provided a quantitative 

 measure of the extent of the damage done. Clinical tests indicated the thymol 

 turbidity reaction to be a valuable indicator of liver dysfunction particularly in 

 infective hepatitis and cirrhosis. Findings were negative or only weakly positive in 

 obstructive jaundice. 



Clinical studies employing the thymol turbidity test and other tests used lor 

 detecting hepatic impairment have been reported by Watson and Rappaport,* 

 Neefe,^ Neefe and Reinhold^ and Mateer et al.-'^-'^ These authors have all as- 

 signed the thymol turbidity test a significant place as an adjunct in studying liver 

 disease. Their results parallel, to a degree, those obtained with the cephalin 

 cholesterol flocculation reaction; however, significant differences in positivity and 

 sensitivity displayed by the two tests on the same sera indicate that the chemical 

 mechanisms of the tests are different. 



In a study of the sensitivity and value of the thymol turbidity and thymol 

 flocculation tests Mateer et al.^-^ showed that the buffer solution with a reaction 

 of pH 7.55, gave more satisfactory results than at pH 7.8 as originally suggested 

 by Maclagan, and could be used for acute as well as chronic cases. With this 

 slightly more acid thymol buffer solution they reported that the sensitivity of 

 the test was greatly increased and that no false positives were obtained. In 

 addition, the modified solution was of equal value in chronic cases and for 

 following the progress of acute impairment. Mateer's observation of the greater 

 sensitivity of the thymol turbidity reagent at pH 7.55 has been confirmed by 

 Neefe^ et al. Bacto-Thymol Turbidity Reagent is prepared according to the 

 modification suggested by Mateer et al.--^ with a reaction of pH 7.55. 



Procedure: 



Measure 0.05 ml. of unheated serum into a dry tube and add 3 ml. of Bacto- 

 Thymol Turbidity Reagent. Allow to stand for one-half to one hour, and 

 examine in a comparator with a black line on a white background against the 

 turbidity standards of Kingsbury et al.^ Bacto-Kingsbury Turbidity Standards 

 are now available. If the turbidity exceeds the 100 mg. per cent standard, dilute 

 with a further measured volume of buffer as required. The result is expressed 

 in arbitrary units equal to the appropriate standard divided by ten with allow- 

 ance for dilution. The standard dilution is 1-60, so that if the final dilution is 

 1-120 and the mixture then matches the 70 mg. per cent tube, the result is 14 

 units. 



-, , f , TT • Standard tube reading X final dilution of serum 



Expressed as a formula : Units = -rrr^ 



bUU 



Normal limits are to 4 units. Tubes showing positive results, as evidenced by 

 turbidity within one hour, if held overnight usually show flocculation. This 



