CSCC/CAMB ABSTRACTS

1 SALIVA LEVELS OF 17-OH PROGESTERONE DURING THE MENSTRUAL CYCLE IN WOMEN

Hofman, L.F. and Klaniecki , J.E., V i rg in ia Mason Research ~ , S ~ t l e , WA 98101

The level of 17-OH progesterone in sal iva has been examined in women by a d i rec t so l id phase radioimmunoassay adapted from an in fan t screening assay fo r 17-OH progesterone. (Hofman, L.F., K laniecki , J.E. and Smith, E.K., Cl in. Chem. submitted.) Eight women co l lec ted sa l iva samples at home and brought them frozen to the laboratory . 17-OH progesterone levels were re la ted to day of the menstrual cycle (day one is the s ta r t o f menstruation). Al l cycles had at leas t a two fold r ise in hormone leve l . Day of i n i t i a l r i se ranged from the 12th to the 15th day of the cycle. Peak values ranged from 20 to I00 ng/L with a mean of 60 ng/L.

Since th is work has been done with an in te res t in devel- oping a home sa l iva tes t to pred ic t ovu la t ion, in four cycles 17-OH progesterone leve ls were compared with urine LH leve ls . (Ovustick, Monoclonal Ant ibodies, 2319 Charleston RD, Mountain View, CA 94043). The LH surge in these cycles ranged from 12th to the 14th day of the cycle. In three cycles the f i r s t 17-OH progesterone peak (the hormone level rises, then drops, then r ises again in sa l iva) was the same day as the LH surge, in the other the day before. However, in every case a detectable r i se (two times the basel ine) occurred one to two days before the LH surge or around 58 hours p r io r to ovu la t ion. (Hof f , J.D., Quigley, M.E. and Yen, S.C.C., J. Cl in. Endocrinol. Metab. 57 792-796 (1983). (This work was supported by an award to L~--F. Hofman from the AACC Endowment Fund.)

2 THYROXIN AND THYROXIN UPTAKE BY FLUORESCENCE POLARIZATION IMMUNOASSAY

Ensland, T., and McNeil, S., MDS Laboratories, Rexdale, Ontario Mgw 6J6.

The analytical performance of thyroxin (T 4) and thyroxin uptake (T 4 U) by fluorescence polarization immunoassay (FPIA) were evaluated on the Abbott TDx analyzer. Reproducibility was excellent: between run CVs for T h assayed singly were less than 8% at hypothyroid levels and less than 5% at euthyroid and elevated levels. CVs for T 4 U were generally less than 3.5%. FPIA values for T 4 correlated with the Abbott RIABEAD procedure (FPIA = 0.9120 * RIA - 0.5158, r = 0.9358). The relationship of T 4 U values by FPIA and T 3 U values HIA is curvelinear and no correlation statistics are calculated. FTI calculated from FPIA results may more accurately indicate thyroid status than the corresponding index based on RIA. At both hypothyroid and hyperthyroid levels, FPIA indicies were verified with either thyrotropin or free thyroxin respectively. Although the TDx generates about one result a minute, analyzers can be used in tandem for greater productivity so that one operator can process at least 40 patients' specimens per hour for both T 4 and T h U. The free thyroxin index (FTI) is calculated automatically by the analyzer.

3 AN EVALUATION OF NEONATAL TSH KITS FOR NEWBORN

SCREENING PROGRAM, Wangp S.T. and Peter, F., Biochemistry Lab. Lab. Serv. Branch, Ministry of Health, Box 9000, Terminal 'A' Toronto, Ontario MSW IR5

We evaluated five commercially available neonatal TSH Kits: Malay, Radioimmunoassay Incorporated (RIA Inc.) Pharmaeia, Becton Dickinson, and ESP Immunodiagnostics for our Newborn Screening Program. The guidelines of realibility and practi- cability of the analytical methods recommended by the Inter- national Federation of Clinical Chemistry were used to assess the kits. The kit from RIA Inc. is using an immunoradiometric method (IRMA), whereas the other four kits apply a radio- immunoassay (RIA) technique. All five kits involve two-day assay procedures. The mean correlation coefficient (r) of the logit-log standard curve ranges from 0.9370 to 0.9901 and the mean dose at 50~ maximum binding (EDso) is from 50 to 268 mU/L of serum.

The intra- and inter-assay precisions of the kits were evaluated by assaying 20 replicates of two quality control specimens every day for five days. The overall precision of the kits ranges from 13 to 25 % CV for 40 mU/L and from 12 to 22 % CV for 120 mU/L of serum. The accuracy of the kits was determined on four replicates each of the Centre for Disease Control (CDC) Proficiency Testing and Quality Control speci- mens, every day for five days. All results on three CDC Pro-

CLINICAL BIOCHEMISTRY, VOLUME 18, JUNE 1985

ficiency Testing specimens (CF4 BO4-BO6) are within the acceptable ranges set by CDE. On the three CDC Quality Con- trol specimens (411-413), kits from Meloy, ESP and Becton Dickinson showed a slightly lower value, while Pharmacia and RIA Inc. gave a slightly higher value than the CDC target values. All five kits appeared to be technically suitable for routine screening.

4 DIRECT MEASUREMENT OF CEA IN SERUM BY ONE STEP ENZYME IMMUNOASSAY, Mattersberger, J., Lenz, H., Naujoks, K., Kleinhsmmer, G., Links, R., *Givner, M.L., and **Frenette, G., Biochemical Res. Ctr., Boehringer-Mannheim GmbH, D-8132 Tutzing, FRG, *Endocrinol. Lab., Div. of Clin. Chem., The Victoria Gen. Hosp., Halifax, N.S., Canada, **Boehringer- Mannheim Canada, Dorva], Quebec.

The purpose was the deve]opment of a simple and reliable non-radioactive assay of CEA (careinoembryonic antigen) in serum. Our assay utilizes two monocional antibodies which recognize two different epitopes on CEA, one is coated on a tube, the other is bound to horse radish peroxidase. Serum (O.I ml) is incubated with enzyme conjugate, unbound conjugate is washed away, substrata is added and produces absorbance directly related to CEA. Results: (a) range, 0-50 ng/ml CEA; (b) sensitivity, 0.5 ng/m]; (c) precision

mean S.D. ~C.V. mean S.D. ~C.V.

within run 6.3 0.2 3.4 47.8 0.6 i.3 between run 6.2 0.5 8.6 51.2 3.7 7.3

Diluted serum samples are linear over range. Recovery studies: 93-107%. No high dose hook effect is detected up to 25 pg/m] CEA. Up to TO pg/ml of non-specific cross-reacting antigen I and normal biliary glycoprotein from lung and liver respectively do not interfere with the assay. Sera specimens (206) from patients with G.I. tract cancer assayed for CEA by our assay give correlation coefficient of 0.94 in comparison to Abbott's EIA assay. Healthy subjects (50) give CEA values of 1.85 ± 0.7 ng/ml. Conclusion: a novel and reliable direct EIA of CEA utilizing monoc]onal antibodies and non- carcinogenic reagents is described.

5 RED CELL FOLATE: AN EASILY OVERLOOKED ASSAY TO QC

Arseneault, J-J., Hospitals In-Common Laboratory Inc. Toronto, Ontario, M3B IY8

A whole blood (RBC) pool was prepared by gently mixing for 1 hour - 0.1g ascorbic acid, 32 mL distilled water, 18 mL ethylene glycol and 5 mL whole blood. This pool is easy to prepare, inexpensive and practical to use. The pool is stable at least 4 months at -20oc. The following mean RBC Folate values for this pool were obtained with our assay (Quanta-Phase Bl2-Folate from BIO-RAD) between July and September 1984:5.1 nmol/L (n = 14; S.D, = 0.3) 4.9 nmol/L (n = 16; S.D. = 0.3) and 4°9 nmol/L (n = 14; S.D. = 0.4).

In mid-October, the RBC pool indicated a sudden substantial and reproducible drop in measured RBC Folate to 3.8 nmol/L; the drop coincided with the introduction of a new lot of reagents. The lower results were confirmed in a comparison of patient results tested with old reagents and retested with the new lot. QC materials used to monitor serum Folate were unaffected by this change.

Table I: RBC and Serum QC Data from 2 Lots of Reagents RBC Control Serum Control

In-House Pool Anemia* Lyphocheck II* n ~ S.D. ~ S.D. ~ S.D.

Lot 1 14 4.9 0.3 3.3 0.5 29 3.6 Lot 2 7 3.8 0.2 3.4 0.3 29 2.8

(x and S.D. in nmol/L) *From ECS Div. of BIO-RAD In conclusion, performance of RBC Folate assay may be

monitored using the described RBC pool. Serum based QC material may not detect changes in the RBC Folate assay although serum and RBC are often tested within the same assay run.

6 PRELIMINARY OBSERVATIONS ON THE SENSITIVITY AND PRECISION OF A NEW I~UNORADIOMETRIC ASSAY FOR THYROTROPIN. Larivi~re, F., Pouliot, M., and Leclerc, P., Dept. of Bioche- mistry, H~pltal du St-Sacrement, Quebec, Qc GIS 4L8

Recent reports on new immunoradiometric assays for thyro- tropin (TSH}, (Cobb, W.E. et al. (1984) Clin. Chem. 30, 1558) and (Seth, J. et al. (1984) Br. Med. J. 289, I~4) seem to confirm that, due to the negative feeda~-ac-k regula- tion of TSH by thyroid hormones, the serum TSH is suppressed in hyperthyroidism. New sensitive immunoradlometric assays (IRMA) for TSH could then be useful tests for distinguishing between normal and hyperthyroid patients or replace the thyrotropin releasing hormone (TRH) test.

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