Sorted By Test Name - Mayo Medical Laboratories

RPTL
9078
Reference Values:
0-2 years: 4.6 ng/mL/hour (mean)*
3-5 years: 2.5 ng/mL/hour (mean)*
6-8 years: 1.4 ng/mL/hour (mean)*
9-11 years: 1.9 ng/mL/hour (mean)*
12-17 years: 1.8 ng/mL/hour (mean)*
Mean data not standardized as to time of day or diet. Infants were supine, children sitting.
Na-depleted, upright (peripheral vein specimen)
18-39 years: 10.8 ng/mL/hour (mean)
2.9-24.0 ng/mL/hour (range)
> or =40 years: 5.9 ng/mL/hour (mean)
2.9-10.8 ng/mL/hour (range)
Na-replete, upright (peripheral vein specimen)
18-39 years: 1.9 ng/mL/hour (mean)
< or =0.6-4.3 ng/mL/hour (range)
> or =40 years: 1.0 ng/mL/hour (mean)
< or =0.6-3.0 ng/mL/hour (range)
*Stalker HP, Holland NH, Kotchen JM, Kotchen TA: Plasma renin activity in healthy children. J Pediatr
1976;89:256-258
Clinical References: 1. Young WF Jr: Primary aldosteronism: A common and curable form of
hypertension. Cardiol Rev 1999;7:207-214 2. Young WF Jr: Pheochromocytoma and primary
aldosteronism: diagnostic approaches. Endocrinol Metab Clin North Am 1997;26:801-827
Reptilase Time, Plasma
Clinical Information: Prolonged clotting times may be associated with a wide variety of coagulation
abnormalities including: -Deficiency or functional abnormality (congenital or acquired) of any of the
coagulation proteins -Deficiency or functional abnormality of platelets -Specific factor inhibitors -Acute
disseminated intravascular coagulation -Exogenous anticoagulants (eg, heparin, warfarin) The
prothrombin time (PT) and activated partial thromboplastin time (APTT) are first-order tests for
coagulation abnormalities and are prolonged in many bleeding disorders. A battery of coagulation tests is
often required to determine the cause of prolonged clotting times. The thrombin time (TT) test is used to
identify the cause of prolonged APTT or dilute Russell's viper venom time (DRVVT). Reptilase time
(RT) test is used to evaluate a prolonged TT. Reptilase is a thrombin-like enzyme isolated from the venom
of Bothrops atrox. Thrombin splits small fibrinopeptides A and B from fibrinogen molecules, producing
fibrin monomer, which polymerizes to form a clot. Reptilase, however, splits off fibrinopeptide A but not
B, which results in fibrin polymerization. In contrast to thrombin and the TT test which are inhibited by
heparin, the RT is normal in the presence of heparin. Similar to the TT test, the RT is prolonged in the
presence of hypofibrinogenemia and dysfibrinogenemia.
Useful For: Evaluation of a prolonged thrombin time (TT): It is mainly used to confirm or exclude the
presence of heparin in the specimen or specimen type Evaluating hypofibrinogenemia or
dysfibrinogenemia in conjunction with the TT and fibrinogen assay
Interpretation: As seen in the following table, reptilase time can help distinguish among the various
causes of a prolonged thrombin time (TT). Thrombin Time Reptilase Time Causes Remarks Prolonged
Prolonged Hypo- or afibrinogenemia Ascertain by determination of fibrinogen Prolonged Prolonged
Dysfibrinogenemia Ascertain by specific assay Prolonged Normal Heparin or inhibitor of thrombin
Differentiate by human TT and/or heparin assays Prolonged Prolonged Fibrin(ogen) split products (FSP)
Ascertain by FSP or D-dimer assay
Reference Values:
14-23 seconds
Clinical References: 1. Greaves M, Preston FE: Approach to the bleeding patient. In Hemostasis
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