Radioimmunoassay of "free thyroxin" in dried blood spots on filter paper - preliminary observations on the effective differentiation of subjects with congenital hypothyroidism from those with subnormal thyroxin-binding globulin and normal subjects.

Abstract In this sensitive, simple method for measuring "free thyroxin" (FT4) in eluates of dried blood spots on filter paper by use of a radioimmunoassay kit (Amerlex Free T4 RIA), the measurable range of FT4 is 1.8 to 57 ng/L (equivalent to the concentration in serum), or 7 to 237 fg/tube. The mean coefficients of variation for within assay-within spots, within assay-between spots, and between assays were 5.3%, 5.0%, and 6.2%, respectively. FT4 in blood spotted on filter paper is stable for at least a month when dried and kept at either -20 degrees C, 4 degrees C, room temperature (about 25 degrees C), or 37 degrees C. The results for FT4 in dried blood spots correlated closely with the free-T4 concentration in serum (r = 0.99). The method can be used to differentiate cases of primary and secondary hypothyroidism from normal subjects and those with subnormal thyroxin-binding globulin. This method may be useful in screening for congenital hypothyroidism, because sample-retesting is not necessary.

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Enzyme immunoassay of free thyroxin in dried blood samples on filter paper.

Clinical Chemistry ◽

10.1093/clinchem/31.5.750 ◽

1985 ◽

Vol 31 (5) ◽

pp. 750-753 ◽

Cited By ~ 8

Author(s):

N Hata ◽

K Miyai ◽

M Ito ◽

Y Endo ◽

Y Iijimi ◽

...

Keyword(s):

Enzyme Immunoassay ◽

Filter Paper ◽

Room Temperature ◽

Normal Subjects ◽

Blood Samples ◽

Double Antibody ◽

Coefficients Of Variation ◽

The Mean ◽

Measurable Range

Abstract We describe a double-antibody enzyme immunoassay for determination of free thyroxin (FT4) in dried blood samples on filter paper, with use of a T4-beta-D-galactosidase complex. The measurable range of FT4 concentration in two 3-mm blood discs, each of which contained about 2.7 microL of blood, was 1.9 to 93 ng/L, as determined by comparison with concentrations of FT4 in known serum standards. FT4 in blood samples dried on filter paper was stable for at least four weeks when kept dry at -20 degrees C, room temperature, or 37 degrees C. The mean coefficients of variation were 7.6% (within assay) and 6.4% (between assays). Results for FT4 by this method correlated well with those for serum determined by radioimmunoassay (r = 0.98). The proposed method can be used to differentiate persons with hyper- and hypothyroidism from normal subjects and those with abnormal concentrations of thyroxin-binding globulin. The procedure seems suited for screening studies.

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Hyperphenylalaninemia Due to Dihydropteridine Reductase Deficiency: Diagnosis by Enzyme Assays on Dried Blood Spots

PEDIATRICS ◽

10.1542/peds.70.3.426 ◽

1982 ◽

Vol 70 (3) ◽

pp. 426-430

Author(s):

Nobuhiro Arai ◽

Kuniaki Narisawa ◽

Hiroshi Hayakawa ◽

Keiya Tada

Keyword(s):

Newborn Infants ◽

Dried Blood Spots ◽

Dihydropteridine Reductase ◽

Simple Method ◽

Blood Spots ◽

Control Value ◽

The Mean ◽

Peripheral Leukocytes ◽

The Stability ◽

Filter Papers

Enzymatic diagnosis of hyperphenylalaninemia due to a deficiency of dihydropteridine reductase (DHPR) has previously been made by assay on liver biopsy samples, cultured skin fibroblasts, cultured lymphoid cell lines, or peripheral leukocytes. These procedures have some disadvantages for the purpose of early diagnosis of the disease. A simple method of DHPR assay using erythrocytes or dried blood spots on filter papers is described. The mean DHPR activity erythrocytes of control subjects was 3.20 ± 0.70 (SD) nmoles/min/mg of hemoglobin, those of two patients were undetectable, and those of obligate heterozygotes for DHPR deficiency were approximately 50% of the mean control value. The assay on erythrocytes required only a 5-µl volume of whole blood for one test. The DHPR activities in dried blood spots on filter papers from 100 normal newborns were 5.77 ± 1.16 nmoles/min per 5-mm diameter disc; those from normal older infants, children, and adults were 3.37 ± 0.72 nmoles/min per disc; and those from two adolescent patients with DHPR deficiency were undetectable. No false-positive results were obtained. The stability of DHPR in dried blood on filter papers was enough to mail samples in an ordinary form to a specialist laboratory. The DHPR assay on erythrocytes of dried blood spots can be easily applied to all newborn infants with hyperphenylalaninemia detected using the Guthrie tests, and will facilitate the quick and confirmative detection of DHPR deficiency among them.

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Simple Screening Methods for Hypoxanthine-Guanine Phosphoribosyltransferase and Adenine Phosphoribosyltransferase Deficiencies Using Dried Blood Spots on Filter Paper

Annals of Clinical Biochemistry International Journal of Laboratory Medicine ◽

10.1177/000456328602300507 ◽

1986 ◽

Vol 23 (5) ◽

pp. 529-532 ◽

Cited By ~ 3

Author(s):

Y Nishida ◽

T Miyamoto

Keyword(s):

Filter Paper ◽

Enzyme Activities ◽

Enzyme Reaction ◽

Normal Subjects ◽

Dried Blood Spots ◽

Screening Methods ◽

Adenine Phosphoribosyltransferase ◽

Blood Spots ◽

Hypoxanthine Guanine Phosphoribosyltransferase ◽

Simple Screening

Simple methods for the detection of hypoxanthine-guanine phosphoribosyltransferase and/or adenine phosphoribosyltransferase deficiencies using dried filter paper blood spots were studied. Enzyme activities in the eluate from dried filter paper blood spots stored for 4 weeks at room conditions were shown to be quite stable. Autoradiographs prepared from dried filter paper blood spots and DE-81 papers soaked with enzyme reaction mixtures containing 14C-hypoxanthine and/or 14C-adenine showed sharp radioactive spots in normal subjects. No activity was evident in the cases of the Lesch-Nyhan syndrome and/or adenine phosphoribosyltransferase deficiency. The methods seem to be suitable for screening.

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Thyroxine-binding globulin capacity and concentration evaluated from blood spots on filter-paper in a screening program for neonatal hypothyroidism.

Clinical Chemistry ◽

10.1093/clinchem/26.3.463 ◽

1980 ◽

Vol 26 (3) ◽

pp. 463-465 ◽

Cited By ~ 5

Author(s):

J H Dussault ◽

J Morissette ◽

J Letarte ◽

H Guyda ◽

C Laberge

Keyword(s):

Congenital Hypothyroidism ◽

Filter Paper ◽

Screening Program ◽

Simple Method ◽

Neonatal Hypothyroidism ◽

Thyroxine Binding Globulin ◽

Blood Spots ◽

Prompt Diagnosis ◽

Blood Spot

Abstract We describe a simple method for evaluating thyroxine-binding globulin capacity and concentration from a single 1-cm blood spot on filter-paper used in a screening program for neonatal hypothyroidism. This method permits prompt diagnosis of about 90% of the infants with thyroxine-binding globulin deficiency in our abnormal low-thyroxine, low-thyrotropin population. There was excellent equivalence between results obtained by our method and by the method of Chopra et al. (J. Clin. Endocrinol. Metab. 35:565, 1972), and minimal overlap between the population with low thyroxine-binding globulin and the low-thyroxine, normal thyrotropin population. We recommend this method to all programs in which a primary thyroxine measurement is used in screening for congenital hypothyroidism.

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Thyroxine-binding globulin capacity and concentration evaluated from blood spots on filter-paper in a screening program for neonatal hypothyroidism.

Clinical Chemistry ◽

10.1093/clinchem/26.3.0463 ◽

1980 ◽

Vol 26 (3) ◽

pp. 463-465

Author(s):

J H Dussault ◽

J Morissette ◽

J Letarte ◽

H Guyda ◽

C Laberge

Keyword(s):

Congenital Hypothyroidism ◽

Filter Paper ◽

Screening Program ◽

Simple Method ◽

Neonatal Hypothyroidism ◽

Thyroxine Binding Globulin ◽

Blood Spots ◽

Prompt Diagnosis ◽

Blood Spot

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Automation of RNA-based biomarker extraction from dried blood spots for the detection of blood doping

Bioanalysis ◽

10.4155/bio-2020-0041 ◽

2020 ◽

Author(s):

Francesco Loria ◽

Michelania Manfredi ◽

Gemma Reverter-Branchat ◽

Jordi Segura ◽

Tiia Kuuranne ◽

...

Keyword(s):

Clinical Study ◽

Elite Athletes ◽

Dried Blood Spots ◽

Recombinant Erythropoietin ◽

Blood Doping ◽

Blood Spots ◽

Average Improvement ◽

Coefficients Of Variation ◽

The Mean ◽

Rna Biomarkers

Aim: Transcriptomic biomarkers originating from reticulocytes measured in dried blood spots (DBSs) may be reliable indicators of blood doping. Methods/results: Here, we examined changes in the expression levels of the erythropoiesis-related ALAS2, CA1 and SLC4A1 genes in DBS samples from elite athletes and volunteers of clinical study with recombinant erythropoietin dose. Conclusion: By comparing the mean intraday coefficients of variation for ALAS2L, ALASLC, CA1 and SLC4A1 between manual and automated RNA extractions, an average improvement was observed, whereas the assessment of interday variability provided comparable results for both manual and automated approaches. Our results confirmed that RNA biomarkers on DBS support are efficient to detect blood doping.

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A COMPARISON OF TWO METHODS FOR MEASUREMENT OF ALDOSTERONE SECRETION RATE IN MAN

Acta Endocrinologica ◽

10.1530/acta.0.0530177 ◽

1966 ◽

Vol 53 (2) ◽

pp. 177-188 ◽

Cited By ~ 4

Author(s):

P. Lund-Johansen ◽

T. Thorsen ◽

K. F. Støa

Keyword(s):

Urinary Excretion ◽

Normal Subjects ◽

Secretion Rate ◽

Aldosterone Secretion ◽

Simple Method ◽

Mean Values ◽

Pathological Conditions ◽

Significant Difference ◽

Derivative Method ◽

The Mean

ABSTRACT A comparison has been made between (A), a relatively simple method for the measurement of aldosterone secretion rate, based on paper chromatography and direct densitometry of the aldosterone spot and (B) a more elaborate isotope derivative method. The mean secretion rate in 9 normal subjects was 112 ± 26 μg per 24 hours (method A) and 135 ± 35 μg per 24 hours (method B). The »secretion rate« in one adrenalectomized subject after the intravenous injection of 250 μg of aldosterone was 230 μg per 24 hours (method A) and 294 μg per 24 hours (method B). There was no significant difference in the mean values, and correlation between the two methods was good (r = 0.80). It is concluded that the densitometric method is suitable for clinical purposes as well as research, being more rapid and less expensive than the isotope derivative method. Method A also measures the urinary excretion of the aldosterone 3-oxo-conjugate, which is of interest in many pathological conditions. The densitometric method is obviously the less sensitive and a prerequisite for its use is an aldosterone secretion of 20—30 μg per 24 hours. Lower values are, however, rare in adults.

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