Cryoactivation of renin in plasma from pregnant and nonpregnant subjects, and its control.

Abstract Plasma renin activity increased by a mean of 7% from baseline values when blood from nonpregnant persons was kept at 0 degrees C for 5 h before incubation. Freezing chilled plasma and thawing it before incubation resulted in a mean increase of 11%. The same procedures used on plasma from normal pregnant women produced mean increases in plasma renin activity of 44 and 89%, respectively. If blood from pregnant women was kept at 0 degrees C for 5 h, and the plasma then separated, frozen, and thawed before incubation, the resulting mean increase in plasma renin activity from baseline values was 160%. We conclude that plasma from pregnant women should be handled at room temperature, or, if samples must be stored, they must be rapidly frozen, then thawed as rapidly as possible before incubation and assay if results are to be reproducible.

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Effect of temperature on plasma renin samples.

Clinical Chemistry ◽

10.1093/clinchem/24.7.1202 ◽

1978 ◽

Vol 24 (7) ◽

pp. 1202-1204 ◽

Cited By ~ 13

Author(s):

F Fyhrquist ◽

L Puutula

Keyword(s):

Plasma Renin Activity ◽

Room Temperature ◽

Plasma Renin ◽

Renin Activity ◽

Effect Of Temperature ◽

Plasma Samples ◽

Hypertensive Patients ◽

Variable Extent ◽

Venous Plasma

Abstract Plasma renin activity was measured in parallel in Na2EDTA-contained plasma samples after storage at -20, 4, and 24 degrees C, and in the lyophilized state. In peripheral venous plasma from 22 hypertensive patients, the activity (range, 0.08-46.7 microgram/liter per hour) remained stable during three days of storage at 4 degrees C, but decreased to a variable extent when plasma was kept at 24 degrees C: in one day by 9.2%, two days by 25.6%, and three days by 74.0%. Values were the same for samples handled at room temperature and chilled to 4 degrees C within 3 h and parallel samples immediately cooled in an icebath and kept at 4 degrees C. Freezing (-20 degrees C) and thawing of plasma was associated with a 22% mean increase in activity (range, 0-83%). Lyophilization resulted in a smaller increase of plasma renin activity (mean 12%, range 0-46%). Blood for renin analysis need not be cooled immediately, but must be cooled to 4 degrees C within 2-3 h. It then is stabe for at least three days. Freezing or lyophilization appears to be associated with some cold activation of "prorenin."

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Cold Promoted Activation of Factor VII(CPA) and Plasma Renin Activity (PRA)

10.1055/s-0039-1687495 ◽

1979 ◽

Author(s):

E. van Royen ◽

K. Hoekman ◽

P. Elte ◽

A. Schellekens

Keyword(s):

Plasma Renin Activity ◽

Pregnant Women ◽

Plasma Renin ◽

Special Care ◽

Renin Activity ◽

Factor Vii ◽

Plasma Samples ◽

Spontaneous Activation ◽

Esterase Inhibitor

The CPA phenomenon occurs in about 20% of the population, 60% of women using contraceptive drugs and 90% of pregnant women. Cpa positive plasma samples show at 4°C spontaneous activation of prekallikrein and factor VII, shortening of the ThrombotestR Time (TT) and consumption of C4 esterase inhibitor. Since kalllkrein may activate prorenin, we related the CPA phenomenon to PRA.A highly significant correlation was found between the shortening of the TT at 4°C and an increase in PRA during storage of random plasma samples.It is concluded that special care should be taken when PRA is determined in CPA positive plasma samples in order to avoid erroneously high PRA levels.

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Should blood samples for assay of plasma renin activity be chilled?

Clinical Chemistry ◽

10.1093/clinchem/24.11.2042 ◽

1978 ◽

Vol 24 (11) ◽

pp. 2042-2043 ◽

Cited By ~ 5

Author(s):

R L Emanuel ◽

G H Williams

Keyword(s):

Plasma Renin Activity ◽

Room Temperature ◽

Plasma Renin ◽

The Other ◽

Renin Activity ◽

Angiotensin I ◽

Blood Samples ◽

Hypertensive Patients

Abstract Collecting blood on ice for renin determination reportedly may produce falsely high results. To assess the probability of this occurring under actual collection conditions, we measured renin activity in duplicate aliquots of plasma from blood samples from 25 hypertensive patients, both supine and upright, and in 10 supine normotensive controls. One aliquot of the blood was collected on ice and processed at 4 degrees C, the other at room temperature. The two aliquots showed no significant differences in renin activity. If anything, values for samples collected at room temperature were higher. Repeat determination on the same specimens stored at--20 degrees C for nine and 12 months revealed no significant changes in results for any samples, although the amount of angiotensin I found in the sample before incubation at 37 degrees C significantly increased. We conclude that it makes little difference at what temperature one collects blood for renin determination, but because of the wide fluctuations in "room" temperature we recommend that blood samples be collected on ice.

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Plasma Renin Activity in Normal Human Pregnancy and in Pregnancy-Associated Hypertension, with Reference to Cryoactivation

Clinical Science ◽

10.1042/cs0590049 ◽

1980 ◽

Vol 59 (1) ◽

pp. 49-53 ◽

Cited By ~ 24

Author(s):

E. D. M. Gallery ◽

G. S. Stokes ◽

A. Z. Györy ◽

J. Rowe ◽

J. Williams

Keyword(s):

Plasma Renin Activity ◽

Pregnant Women ◽

Sodium Intake ◽

Plasma Renin ◽

Normal Pregnancy ◽

Renin Activity ◽

Central Feature ◽

Plasma Renin Concentration ◽

Significant Difference ◽

In Pregnancy

1. Because hypertension is the central feature of pre-eclampsia, and because plasma renin activity is known to be elevated in normal pregnancy (with conflicting results published for pre-eclampsia), a prospective study of plasma renin activity was conducted in pregnancy, under conditions of a fixed sodium intake, in 178 initially normotensive volunteer subjects. Thirty of these women developed pregnancy-associated hypertension (pre-eclampsia) in the third trimester. 2. There was a significant elevation of plasma renin activity from the published values for non-pregnant women, throughout gestation in normotensive women. There was no significant difference, at any stage of gestation, between the values for normal women and those who developed pregnancy-associated hypertension. 3. The extent of cryoactivation of renin, produced by usual collection procedures, was investigated in a subgroup of the total population. It was highly significant and quite variable, but was similar in those who developed pregnancy-associated hypertension and in normal pregnant women. The mean increase in plasma renin concentration in maximally cryoactivated samples was 16-fold. 4. Neither measurement of peripheral plasma renin activity nor of cryoactivatable plasma renin concentration is of value in distinguishing between normal pregnant women and those destined for, or with pregnancy-associated, hypertension.

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