Long‐term stability of thyroid hormones and DNA in blood spots kept under varying storage conditions

Ezzi, Asmahan A. El; El‐Saidi, Mohammed A.; Kuddus, Ruhul

doi:10.1111/j.1442-200x.2010.03101.x

Cited by 8 publications

(6 citation statements)

References 13 publications

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“…All plasma samples were stored for approximately 1 year at −20°C before analysis of T 4 and TSH. According to the literature (El Ezzi et al 2010; Männistö et al 2007), the concentrations of T 4 and TSH are very stable over time.…”

Section: Methodsmentioning

confidence: 95%

Lithium in Drinking Water and Thyroid Function

Broberg

Concha

Engström

et al. 2011

Environ Health Perspect

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BackgroundHigh concentrations of lithium in drinking water were previously discovered in the Argentinean Andes Mountains. Lithium is used worldwide for treatment of bipolar disorder and treatment-resistant depression. One known side effect is altered thyroid function.ObjectivesWe assessed associations between exposure to lithium from drinking water and other environmental sources and thyroid function.MethodsWomen (n = 202) were recruited in four Andean villages in northern Argentina. Lithium exposure was assessed based on concentrations in spot urine samples, measured by inductively coupled plasma mass spectrometry. Thyroid function was evaluated by plasma free thyroxine (T4) and pituitary gland thyroid-stimulating hormone (TSH), analyzed by routine immunometric methods.ResultsThe median urinary lithium concentration was 3,910 μg/L (5th, 95th percentiles, 270 μg/L, 10,400 μg/L). Median plasma concentrations (5th, 95th percentiles) of T4 and TSH were 17 pmol/L (13 pmol/L, 21 pmol/L) and 1.9 mIU/L, (0.68 mIU/L, 4.9 mIU/L), respectively. Urine lithium was inversely associated with T4 [β for a 1,000-μg/L increase = −0.19; 95% confidence interval (CI), −0.31 to −0.068; p = 0.002] and positively associated with TSH (β = 0.096; 95% CI, 0.033 to 0.16; p = 0.003). Both associations persisted after adjustment (for T4, β = −0.17; 95% CI, −0.32 to −0.015; p = 0.032; for TSH: β = 0.089; 95% CI, 0.024 to 0.15; p = 0.007). Urine selenium was positively associated with T4 (adjusted T4 for a 1 μg/L increase: β = 0.041; 95% CI, 0.012 to 0.071; p = 0.006).ConclusionsExposure to lithium via drinking water and other environmental sources may affect thyroid function, consistent with known side effects of medical treatment with lithium. This stresses the need to screen for lithium in all drinking water sources.

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Section: Methodsmentioning

confidence: 95%

Lithium in Drinking Water and Thyroid Function

Broberg

Concha

Engström

et al. 2011

Environ Health Perspect

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“…Although the pertinent literature is quite limited (2)(3)(4)(5)(6)(7)(8), it is undeniably important to establish the best drying and storage conditions of blood samples collected on filter paper for newborn screening. The samples are frequently exposed to different climate conditions during drying and transport to the laboratories, a fact that may influence the test results.…”

Section: Discussionmentioning

confidence: 99%

“…Despite the simplicity of this method, which does not require venipuncture and simplifies sample transportation from distant regions to a central laboratory, questions arise about the possible interference of sample drying, storage and transportation under different physical conditions and of the quality of filter paper with the stability of the hormones (2)(3)(4)(5)(6)(7)(8).…”

Section: Introductionmentioning

confidence: 99%

Effects of drying and storage conditions on the stability of TSH in blood spots

Magalhães¹,

Miranda²,

Vilar³

et al. 2018

Archives of Endocrinology and Metabolism

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Objective: To evaluate the influence of sample drying and storage temperature on TSH stability in neonatal screening. Subjects and methods: Blood samples from 29 adult volunteers as a surrogate for neonatal blood (10 with normal TSH, 9 with overt hypothyroid and 10 with subclinical hypothyroidism) were spotted on filter paper and dried at 22°C or 35°C for 3 hours. The samples were then stored at 22°C, -4°C, or -20°C, and TSH measurements were performed at day 0 (D0), D7, D30, D60, D180, and D360 of storage. Results: The drying temperature did not interfere with TSH measurement on D0. TSH values remained stable up to D30 when stored at 22°C and were stable up to D60 when stored in a refrigerator or freezer. Samples stored at 22°C had a greater decrease in TSH values than samples stored in a refrigerator or a freezer. Conclusions: Freezer storage is not advantageous compared to storage in the refrigerator. At the end of one year, if confirmation of the initial result is required, a reduction of TSH concentrations should be taken into account. Arch Endocrinol Metab. 2018;62(2):201-4

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“…Sera were frozen at −80°C for up to 8.5 months and subjected to 2 freeze‐thaw cycles. Previous studies have shown that dog and cat serum TT4 concentrations remain stable for 35 days at −20°C, and that serum TT4 concentrations in humans remain stable for 6.5 years at −20°C, but no published data are available to our knowledge on the effects of long‐term storage or freeze‐thaw cycles on serum TT4 concentrations in dogs and cats. Given that the MTT4 was repeated at the same time as the CTT4 and ITT4, no effect of storage or freeze‐thaw cycle on the method comparison should have occurred.…”

Section: Discussionmentioning

confidence: 99%

“…The MTT4 concentrations Altman plots showed an increasing difference in dogs with TT4 concentrations >5 μg/dL (64.36 nmol/L).This difference would be unlikely to change clinical decisions regarding diagnosis of either iatrogenic oversupplementation or a functional thyroid tumor. The stronger proportional bias evident at values >8 μg/dL (102.98 nmol/L) on Bland-Altman plots would be unlikely to change days at −20 C,9 and that serum TT4 concentrations in humans remain stable for 6.5 years at −20 C,28 but no published data are available to our knowledge on the effects of long-term storage or freeze-thaw cycles on serum TT4 concentrations in dogs and cats. Given that the MTT4 was repeated at the same time as the CTT4 and ITT4, no effect of storage or freeze-thaw cycle on the method comparison should have occurred.…”

mentioning

confidence: 99%

Comparison of 2 assays for measuring serum total thyroxine concentration in dogs and cats

Wolff

Bilbrough

Moore

et al. 2020

Veterinary Internal Medicne

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Background No gold standard assay for serum total thyroxine (TT4) concentration in small animals exists. The Microgenics DRI TT4 (MTT4) assay is used by most reference laboratories. Hypothesis/Objectives IDEXX Catalyst Total T4 (CTT4) and Immulite 2000 TT4 (ITT4) results will agree with MTT4 results. Animals Residual small animal sera were randomized before reanalysis (dogs, CTT4 versus MTT4: n = 176, ITT4 versus MTT4: n = 74; cats, CTT4 versus MTT4: n = 319, ITT4 versus MTT4: n = 79). Methods Validation and method comparison study. Serum TT4 concentration was measured on all analyzers. Pairwise Pearson correlation, cumulative sum linearity test, regression, and Bland‐Altman method were performed. Results CTT4 versus MTT4 in dogs: constant bias (y‐intercept) was 0.10 μg/dL (95% confidence interval [CI], 0.05‐0.15), proportional bias (slope) was 0.86 μg/dL (95% CI, 0.83‐0.89); in cats, constant bias was 0.13 μg/dL (95% CI, 0.08‐0.20) and proportional bias was 1.01 μg/dL (95% CI, 0.98‐1.03), but the test for linearity failed. Bland‐Altman plots identified increasing disagreement with increasing serum TT4 concentrations. ITT4 versus MTT4 in dogs, constant bias was 0.14 μg/dL (95% CI, 0.04‐0.22) and 0.22 μg/dL (95% CI, 0.09‐0.33) for cats; proportional bias was 0.76 (95% CI, 0.72‐0.80) for dogs and 0.71 (95% CI, 0.69‐0.74) for cats. Conclusions and Clinical Importance Differences in CTT4 and MTT4 results affect interpretation at higher serum TT4 concentrations. The ITT4 proportional bias will underestimate serum TT4 concentrations in dogs and cats, compared to MTT4. Serial TT4 measurements should be done using the same assay.

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Long‐term stability of thyroid hormones and DNA in blood spots kept under varying storage conditions

Cited by 8 publications

References 13 publications

Lithium in Drinking Water and Thyroid Function

Lithium in Drinking Water and Thyroid Function

Effects of drying and storage conditions on the stability of TSH in blood spots

Comparison of 2 assays for measuring serum total thyroxine concentration in dogs and cats

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