Biomedical subjects

R Sapin

Publications and source records attributed to R Sapin.

94 records · Page 6Linked to original sources

PubMedDate not supplied

[Simultaneous determination of blood insulin and plasma C-peptide levels. Value during assessment of glucose tolerance, especially in obese subjects (author's transl)].

Insulin secretion is assessed by simultaneous radioimmunological assay of insulin (R.I.I.) and C-peptide (R.I.C.P.) levels under basal conditions, and after stimulation by oral or intravenous glucose administration. Subjects with abnormal glucose tolerance demonstrate an increase in the ratios R.I.C.P. divided by glucose and R.I.C.P. divided by R.I.I. after fasting, increase in R.I.I. and R.I.C.P. occurring later and lasting longer after glucose loading. These anomalies are observed in both obese subjects and those with normal body weights. Simultaneous determination of R.I.I. and R.I.C.P. levels appears of value in a limited number of cases where glucose loading tests do not supply precise information on the quality of glucose tolerance. Obese subjects, in whom abnormal hyperglycemia levels provoked by oral glucose are observed, but in whom the peripheral glucose assimilation coefficient is normal, can be considered to be non-diabetic as shown by the levels of R.I.I. and R.I.C.P. and more particularly by the molar ratio R.I.C.P. divided by R.I.I.

Administration, Oral↗

PubMedDate not supplied

[Effect of surgery on the level of total and free thyroid hormones, reverse T3 and TSH].

Changes in total and free thyroid hormones, reverse triiodothyronine (rT3) and TSH were followed in 64 patients undergoing surgery and divided into three groups according to nature of surgery. Group I patients underwent extraperitoneal surgery, group II mild and group III heavy intraperitoneal surgery. A significant fall in total and free triiodothyronine (T3), a rise in rT3, free thyroxine (FT4) and in TSH were noted in each group after surgery, while total T4 levels remained unchanged. There was no correlation between the change in thyroid hormones and TSH. These changes are more marked in groups II and III than in group I. The rT3/T3 ratio was more elevated after surgery in group III than in group II. Thus the severity of the stress induced by surgery may interact with the mechanism of peripheral T4 conversion. The rise in FT4 may be interpreted as a consequence of the presence of an inhibitor of thyroid-hormonal binding to serum proteins. The slight increase in TSH levels seems rather due to stress than to a feed-back adaptation. The ratio rT3/T3 appears as an index of severity and prognosis.

Adult↗

PubMedDate not supplied

[Thyroid function in patients with alcoholic cirrhosis (author's transl)].

Total serum thyroxine (T4), total serum triidothyronine (T3), thyrotropin (TSH) and TRH induced TSH release have been measured in 50 clinically euthyroid men with alcoolic cirrhosis and compared to 20 age matched control men in order to determine the thyroid status in cirrhosis. Free serum thyroxin (FT4), free triiodothyronine (FT3) and reverse T3 (rT3), were measured in 34 patients. In these patients, a clinical and biological index was devised to score the severity of the disease. Finally, thyroxine-binding-globulin (TBG) levels were measured in 20 patients. In cirrhotics, the mean total T4 level is normal but the mean T3 level is markedly reduced: FT4 is slightly raised and FT3 is decreased. Serum rT3 levels are often very high and correlated in T3. Basal TSH concentration were slightly significantly higher than normal; the mean magnitude of TSH responses to TRH is comparable to controls but the individual responses are very variable, insufficient or exaggerated, and non correlated with other thyroid function tests. The mean TBG level is also normal and non correlated with total free thyroid hormones. Correlation of thyroid function tests with liver function showed significant correlations between T3, FT3, rT3 or TSH and serum albumin concentration and particularly between T3, rT3 and the clinical and biological index. So the ratio rT3/T3 may be proposed as a valuable index of prognosis and severity of the disease. In conclusion, in alcoholic cirrhosis, thyroid function and regulation are characterized by normal T4 and low T3 levels related to reduced extrathyroidal T4 and T3 conversion levels - and thus maintain the euthyroid state - and by a hypothalamo-pituitary dysfunction. These alterations are related to the degree of liver dysfunction.

Humans↗

PubMedDate not supplied

[Thyroglobulin assay ambiguities].

Thyroglobulin immunometric "sandwich" assays (IMA) have taken over competitive radioimmunoassays, but this assay remains problematic. A human thyroglobulin reference material (CRM 457) has been prepared but is not widely used. That constitutes the main cause of very marked between kit variability of thyroglobulin results. High-dose hook effect, which can falsely decrease the result of a serum with high concentration of thyroglobulin, is not exceptional in one-step assays and should be systematically checked. Selection of monoclonal antibodies with no cross-reactivity with anti-thyroglobulin autoantibodies or of polyclonal antibodies with very high affinity, have reduced the frequency of interference due to autoantibodies, but did not abolish it. Recovery test is used to detect such interference, but with insufficient sensitivity. In fact, recovery determination can be influenced by the nature of thyroglobulin added to the serum (not identical to endogenous thyroglobulin), by the delay of incubation of exogenous thyroglobulin and serum autoantibodies and by the amount of added thyroglobulin. In addition, recovery is often wrongly expressed as the observed/theoretic ratio of final concentrations instead of added concentrations. In untreated Graves' disease patients and despite normal recovery test, thyroglobulin measured by IMA is lower when anti-thyroglobulin autoantibodies are present. Consequently, thyroglobulin result should be interpreted in function of presence or absence of autoantibodies. Development of total (free and autoantibody bound) thyroglobulin assay would be useful to evaluate assay and recovery test performances.

Bias↗