Observations on the Nature of the Underlying Disorder and the Occurrence of Associated Plasma Transport Abnormalities in a Patient with an Idiopathic Increase in the Plasma Thyroxine- binding

Sidney H. Ingbar, … , Christine Waterhouse, Paul Cushman

J Clin Invest. 1964;43(12):2266-2271. https://doi.org/10.1172/JCI105100.

Research Article

Find the latest version: https://jci.me/105100/pdf Journal of Clinical Investigation Vol. 43, No. 12, 1964

Observations on the Nature of the Underlying Disorder and the Occurrence of Associated Plasma Transport Ab- normalities in a Patient with an Idiopathic Increase in the Plasma Thyroxine- binding Globulin*

SIDNEY H. INGBAR, CHRISTINE WATERHOUSE, AND PAUL CUSHMAN t (From the Thorndike Memorial Laboratory, Second and Fourth [Harvard] Medical Services, Boston, City Hospital, and the Department of Medicine, Harvard Medical School, Boston, Mass., and the Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, N. Y.)

Since its discovery in 1952, much has been sponse to pregnancy or to the administration of learned concerning the thyroxine (T4)-binding estrogenic hormones, studies of these three pro- globulin of human plasma (TBG) [cf. Reviews teins, as well as the iron-binding globulin (trans- (1, 2)]. Although its concentration in plasma ferrin), in the serum of this patient were conducted has not been directly measured and is presum- in the basal state and during administration ably very low, the capacity of TBG to bind T4 is of large doses of diethylstilbestrol. The re- readily measured and is normally about 20 ug sponses of TBG and to an anabolic per 100 ml of serum or plasma (1). Recently, steroid, norethandrolone, were also assessed. several patients have been described in whom the T4-binding capacity of TBG is either greatly in- Methods creased or decreased, apparently on a hereditary Case history. Patient F. H. (Strong Memorial Hos- basis (3-8). Physiological studies in such pa- pital no. 46-32-67), a 66-year-old white female, was first tients have contributed much to a formulation of seen in 1958 and complained at that time of episodes of the role of this in the peripheral metabo- giddiness and vertigo, anxiety, tachycardia, and diaphore- lism of T4 (3, 5, 7, 8). On the other hand, little sis of about six months' duration. Weight loss, heat of intolerance, tremor, and palpitations were denied. A has been done to elucidate either the cause the goiter had been noted 40 years earlier and had not protein abnormality itself or the presence of asso- changed in the interim. The patient denied having re- ciated abnormalities in other plasma transport ceived any iodine-containing or hormonal medication. . Physical examination revealed the blood pressure to be The availability of a patient with an apparently 100/85, the pulse rate 88. The thyroid gland was dif- in fusely enlarged, apparently without thrill, bruit, or nod- idiopathic increase the T4-binding capacity of ules. There were no physical signs of hypermetabolism. TBG has made possible further studies of this Significant laboratory data included the following: disorder. Since [cf. Review (9)] BMR, + 12%,, + 3%o; thyroidal 24-hour I's' uptake, 20%, and the corticosteroid-binding globulin (trans- 22%; serum protein-bound iodine (PBI), 11.2, 11.6, 10.6, cortin) (10-14), like TBG (15-17), normally in- 9.2 ,ug per 100 ml. trial of methimazole crease in concentration or in re- In view of the increased PBI, a binding activity was initiated. At a dosage of 30 mg daily, symptoms ap- * Submitted for publication June 29, 1964; accepted parently cleared, but the PBI remained 9.0 and 9.2 /Ag per July 27, 1964. 100 ml after 8 months of treatment. When the dose of Supported in part by research grant no. AM-00267-10 methimazole was increased to 40 mg daily, clinical signs from the National Institute of Arthritis and Metabolic of myxedema appeared, and the PBI declined to 0.9 ,ug Diseases, Bethesda, Md., and in part by U. S. Public per 100 ml. Methimazole was discontinued, and several Health Service research grant no. FR 44-03 from the weeks later, in May of 1960, 5 mc of In was adminis- Division of Research Facilities and Resources, National tered. The patient was asymptomatic at this time and Institutes of Health, Bethesda, Md. has remained so subsequently, although her thyroid de- t Present address: St. Luke's Hospital, New York, creased in size. In March 1961, laboratory tests revealed: N. Y. BMR, -7%, -5%O; PBI, 10.7 /Ag per 100 ml; serum 2266 IDIOPATHIC INCREASE IN TBG 2267 butanol extractable iodine, 8.8 ,ug per 100 ml; 24-hour thyroidal I3' uptake, 38%, decreasing to 5% after 7 days of treatment with 3,5,3'-triiodothyronine, 100 ,ug daily. In June 1961, an increase in the binding activity of 'o _ 0 0 0000 TBG was considered as the possible cause of her ab- 4t4 0 O 00 0\ U) normal PBI. Electrophoretic studies of her serum re- vealed the T4-binding activity of TBG to be greatly in- I - in 00 r 04 tn 440 - 0 ,I.o04- ' creased. In view of the persistently normal values for u4 CN o - BMR and thyroidal I131 uptake, both before and after .0 I'31 therapy, and the normal thyroid suppression test, it oE 4) .% would appear likely that the patient's persistently in- 00 N o creased PBI was never due to thyrotoxicosis, but was, 1') instead, a consequence of increased hormonal binding in the plasma. =.4 In August 1962, the patient was admitted to the Strong Memorial Hospital to receive a 3-week course of diethylstilbestrol, 30 mg daily. The control cervical '0o 00 0 smear revealed no evidence of estrogenic effect. A pro- 0* _44- gressive effect was noted during treatment, however, Cd and was marked by the time diethylstilbestrol was dis-

0 0 u) m o 0u)Cu 00Cr continued. Withdrawal vaginal bleeding followed a 0o'.nn 13 (1 14f\ 0 44 0 few days thereafter. 0 The patient was readmitted in November 1962 to re- 0t 4 U4s cq 0 (7 It'O o oc ceive a 3-week course of norethandrolone, 50 mg daily. During the treatment period, serum glutamic-oxalacetic o44 4.) 0 transaminase values increased from 20 to 60 U. Serum 00 0 t 0000tt-00 000 .0 bilirubin upon completion of therapy was 1 mg per 100 ml. .0 0 Balance studies performed during and after the a .k ot-cl C14 + ,O -9c4 treatment period revealed that norethandrolone induced o Fs in Mc4000 en 00040t0 significant nitrogen retention. 4en enX 00 u CNmM ) 4N- 000X In July of 1963, the patient was readmitted for a 44*4 second course of diethylstilbestrol treatment in order to 0 ~o .0F tne\0 C1400 f'14 '.4.4'3' verify the previously observed findings with regard to ._ a . the effects of this agent on T4-binding and to assess its 00-00 Lnnin c Lnm(4C4n to0 000Lto c ._ 4o ) bO a effects on other plasma transport proteins. o44 .0 Procedure. ._50 Thyroxine-binding capacities of TBG and H H thyroxine-binding prealbumin (TBPA) in serum were 0>4 measured by methods described in detail earlier, em- 0.x ploying paper electrophoresis in Tris-maleate buffer, pH .00 8.6 (7). Concomitantly, the distribution of tracer quan- 0 .04- t4 ''.3' "200'U- tities of P`31-labeled thyroxine, reflecting the binding of D>4c0 4 the endogenous hormone, was also assessed. Analyses 0 for the proportion of unbound T4 in serum were carried 0 3N _ )CZ 4 -00 00044 out by an equilibrium dialysis technique, recently de- 000 0 scribed in abstract form (18), to be described in detail la0 in a later communication. Serum PBI was measured by '.3 e 204e '2 b b4c 00' b440 IC nSo-oZ0.4 ._ a modification of the method of Zak (19). Plasma .5 17-OH corticosteroids were analyzed by the method of -.4 . - Hu m Peterson, Karrer, and Guerra (20), and H .c concentrations by the method of Daughaday, Adler, 0_>4 Mariz, and Rasinski (14). Ceruloplasmin was meas- 4)0 0 0 ured by the method of Scheinberg and Morell (21). a11 Serum iron-binding were measured capacities by the .0 method of Peters, Biovanniello, Apt, and Ross (22). 0 Coo o to o 0o > 4 Results 50x x aO a 11 Results obtained are presented in Table I and Figure 1. In the basal state, the patient's PBI on 2268 S. H. INGBAR, C. WATERHOUSE, AND P. CUSHMAN *-- P81 (Ag//COOmL) (28.2 per 100 ml) were within normal limits, x-x TBG Binding COacity (,ug r7 //OOmL x /O -') /ug &- --& Free 74 (%ftofo/x /02) as was the concentration of ceruloplasmin (25.4 o-o Free T4 Iodine (gg//OOmL x /03) mg per 100 ml). Total serum iron-binding ca- DIETHYLSTILBESTROL NORETHANDROLONE was at the upper (30 mg/day) (50mg/day) pacity limit of the normal range 12 (356 and 404 ptg per 100 ml), although serum iron 'o0 was normal (152 and 142 ug per 100 ml). 0~ 0 Response to diethylstilbestrol. During two 8 separate 3-week trials of diethylstilbestrol, no sig- 61- x A nificant change in the PBI, in the proportion of 4 unbound T4, or in the concentration of free T4-

or- Q iodine in the serum occurred. The T4-binding 2 - capacity of TBG showed little, if any, response I to estrogen administration. During the first trial, 0 1 2 3 0 2 3 WEEKS OF TREATMENT WEEKS OF TREATMENT the binding capacity was 52 ug per 100 ml in the FIG. 1. EFFECT OF ESTROGENIC AND ANABOLIC STEROIDS basal state and 63 per 100 ml after 3 weeks of ON THE TRANSPORT OF THYROXINE IN THE SERUM OF A therapy. During the second trial, comparable PATIENT WITH AN IDIOPATHIC INCREASE IN THYROXINE- values were 56 and 60 Mg per 100 ml, respectively. BINDING GLOBULIN. PBI = protein-bound iodine; TBG = thyroxine (T4) -binding globulin. The per cent of endogenous T4 bound by TBG increased slightly and that bound by TBPA de- repeated determinations since June of 1961 ranged creased. In contrast to these negligible changes in the between 9.2 and 8.3, averaging 9.0 Mg per 100 ml. Thyroidal I131 uptake and basal metabolic rate binding of thyroxine, pronounced increases in the of were within normal limits. Thyroxine-binding concentration cortisol, transcortin, and cerulo- occurred during administration of estro- capacity of TBG, measured on four occasions gen. Total serum and serum during a 25-month period, ranged between 50 and iron-binding capacity iron were not significantly affected. 56 Mg per 100 ml of serum and averaged 54 Mug Response to anabolic steroid. In contrast to per 100 ml.' The T4-binding capacity of TBPA the relative lack of change in T4-binding that was moderately decreased, averaging 47 jMg per 100 ml. Approximately 75% of endogenous T4 occurred during administration of diethylstilbes- trol, pronounced changes in T4-binding occurred was associated with TBG, 15% with TBPA, and the remainder with . during administration of norethandrolone. The thyroxine-binding capacity of TBG decreased to In control studies, the per cent of unbound or normal, the PBI to the lower limit of the normal free thyroxine in the patient's serum was sub- range. Concomitantly, the proportion of unbound normal (0.027 and 0.024%o) and was similar to thyroxine increased to values slightly in excess of the values seen during normal pregnancy. Val- normal, with the result that the concentration of ues for the concentration of free T4-iodine, cal- free thyroxine iodine remained essentially un- culated as the product of the per cent of free T, changed. The T4-binding capacity of TBPA in- and the PBI, averaged 0.0024 Mug per 100 ml, well creased from its low basal value, but did not come within the normal range. Plasma 17-OH corticoid concentration (13 Mug into the normal range. The proportions of en- dogenous T4 associated with TBG and TBPA, per 100 ml) and transcortin-binding capacity which in the basal state were increased and de- 1 By the methods employed in the present studies, creased, respectively, gradually came into or near normal values are: T4-binding capacity of TBG, 22 jug the normal range. per 100 ml (range, 18 to 25) ; T4-binding capacity of Serum iron-bi'nding capacity was not significantly TBPA, 140 ,ug per 100 ml (range, 100 to 200); distri- altered, but serum iron concentration decreased. bution of a tracer concentration of labeled T4 (en- Binding capacities of transcortin and cerulo- *dogenous distribution), TBG, 45%, TBPA, 40%o, albu- plasmin were not measured at this time. Nitrogen min, 15%; free T4, 0.043 0.008%o of total (mean + SD); free T4-iodine, 0.0024 + 0.0007 ,ug per 100 ml (mean retention was observed during the treatment :SD). period. IDIOPATHIC INCREASE IN TBG 2269 Discussion in the serum, a response similar to that elicited in normal subjects (23). Studies of the disturbance in protein From these and other findings it is possible to that occurs in states accompanied by alterations draw several inferences concerning the nature of in TBG are hampered current by inability to the underlying disorder in patients with idiopathic measure the concentration of this protein in the increase in TBG, at least to the extent to which in those states as idio- plasma. Thus, designated this patient may be typical of others. It seems pathic increases or decreases in the binding ac- likely that the increased T4-binding by TBG in tivity of TBG, it is not known whether the actual this patient's serum, and in other states associated concentration of protein is abnormal or whether with increased TBG, reflects an in its structure is altered in such a way as to change increase the actual concentration of this protein. Such a its molecular capacity. Similar un- T4-binding change must result from increased synthesis or certainty applies both to the increases in T,-bind- decreased the ing by TBG that occur during pregnancy or es- degradation of protein, or both. Although one cannot presently choose between trogen administration and to the decreases that these possibilities, it would appear that the factors are induced by androgenic or anabolic steroids.2 which increased this patient's TBG were the same In the present patient, the T4-binding capacity as those that normally increase TBG in response of TBG, the PBI, and the per cent of free T4 in to estrogen. A pre-existing maximal activation of the serum were all within the range to be expected this mechanism would explain the failure of TBG either during normal pregnancy or in response to increase further when estrogen was adminis- to large quantities of estrogen (15-17). Neither tered. On the other hand, the contrary or antago- of these explanations of the abnormality was nistic response to androgenic or anabolic steroids tenable, however, since the patient was postmeno- was apparently retained. pausal and the cervical smear revealed no evidence From the present studies it is additionally ap- of estrogenic effect. Thus, her disorder appears parent that the abnormality in protein metabolism, to merit the designation "idiopathic increase in evident in the increased TBG, was not general to TBG." other proteins whose concentrations in the plasma Although the patient's increased TBG could are normally increased by estrogens. Concentra- not be ascribed to estrogen, evidence was obtained tions of ceruloplasmin and transcortin were nor- that both genital and extragenital effects of estro- mal in the basal state and, as might therefore be gen could be elicited. Intense estrogenic effect on expected, demonstrated a normal increase in re- the cervix and vaginal bleeding followed adminis- sponse to estrogen therapy. tration and withdrawal, respectively, of diethyl- In view of the existing data concerning trans- stilbestrol. In addition, this agent evoked an in- ferrin, studies of this protein in the patient's se- crease in the concentrations of transcortin and rum were inconclusive. Concentrations of trans- ceruloplasmin in the plasma, a response similar ferrin are usually increased during normal preg- to that seen in normal individuals (9-14). Al- nancy, but there is considerable overlap between though the patient responded to estrogen in these values usually found in pregnancy and the rather respects, the patient's already increased TBG was broad normal range [cf. Review (24)]. Further- unaffected by diethylstilbestrol in a dosage and more, it is not certain whether the increase in the duration that normally increase TBG greatly. concentration of transferrin that occurs during Doses of anabolic steroid, sufficient to induce ni- pregnancy is due to a relative iron deficiency or trogen retention, in contrast, lowered the TBG whether transferrin is estrogen-responsive, like and PBI and increased the proportion of free T4 TBG, transcortin, and ceruloplasmin. Values for the total iron-binding capacity of the present 2 For purposes of brevity, an increase or decrease in patient's serum were at the upper limit of normal, the binding capacity of TBG will henceforth be re- and ferred to merely as an increased or decreased TBG, although no increase was elicited by diethyl- respectively. These terms, as herein used, do not indicate stilbestrol, it is not known whether this would that the concentration of the protein is necessarily normally be expected. increased. Finally, the present studies provide further evi- 2270 S. H. INGBAR, C. WATERHOUSE, AND P. CUSHMAN dence of the physiological consequences of T4-bind- the serum were normal in the basal state and in- ing. It is generally agreed that although the pro- creased normally during administration of estrogen. portion of free T4 may vary in diverse states, the It is concluded that in this patient, at least, physiologically important variable is the concen- the increase in TBG is not associated with ab- tration of free T4 in the plasma. In the present normalities in other estrogen-sensitive transport patient, despite a substantial increase in the total proteins and may be due to an estrogen-inde- hormonal concentration, the proportion of free pendent activation of the same mechanism by hormone, not heretofore measured in this syn- which estrogen normally increases TBG. drome, was decreased. As a result, the concen- tration of free T4-iodine was normal, and this was Acknowledgments associated with a normal metabolic state and nor- mal thyroid function. When, on the other hand, We are indebted to Miss Nancy A. Dawber for ex- the binding of T4 was decreased by norethandro- cellent technical assistance and are grateful to Dr. James H. Jandl, Boston, Mass., for analyses of serum lone and the proportion of free hormone increased, iron and iron-binding capacities, to Mrs. Ida Mariz in the the hormonal concentration in the blood declined laboratory of Dr. William H. Daughaday, St. Louis, until the free T4-iodine was within the normal Mo., for analyses of plasma cortisol and corticosteroid- range and the patient remained metabolically nor- binding globulin, and to Dr. I. Herbert Scheinberg, mal. These findings strengthen further the now New York, for analyses of ceruloplasmin. well-supported hypothesis that both the homeo- static mechanisms which regulate thyroid function References and the metabolic state of the patient are con- 1. Robbins, J., and J. E. Rall. Proteins associated with ditioned by the concentration in plasma of free or the thyroid hormones. Physiol. Rev. 1960, 40, unbound, rather than total, T4 (1, 2). 415. 2. Ingbar, S. H., and N. Freinkel. Regulation of the peripheral metabolism of the thyroid hormones. Summary Recent Progr. Hormone Res. 1960, 16, 353. 3. Beierwaltes, W. H., and J. Robbins. Familial in- Studies have been performed in a 66-year-old, crease in the thyroxine-binding sites in serum alpha postmenopausal female whose serum protein- globulin. J. clin. Invest. 1959, 38, 1683. bound iodine (PBI) was abnormally high despite 4. Beierwaltes, W. H., E. A. Carr, Jr., and R. L. normal thyroid function and a normal basal meta- Hunter. Hereditary increase in the thyroxine- bolic rate. Electrophoretic analyses indicated that' binding sites in the serum alpha-globulin. Trans. the increased PBI was associated with an idio- Ass. Amer. Phycns 1961, 74, 170. 5. Florsheim, W. H., J. T. Dowling, L. Meister, and pathic increase in the binding activity of the R. E. Bodfish. Familial elevation of serum thy- plasma thyroxine (T4)-binding globulin (TBG). roxine-binding capacity. J. clin. Endocr. 1962, 22, Although the T4-binding capacity of TBG was in 735. the range usually observed in pregnant patients 6. Tanaka, S., and P. Starr. A euthyroid man without or those receiving large doses of estrogen, no evi- thyroxine-binding protein. J. clin. Endocr. 1957, dence of endogenous excess of estrogen could be 19, 485. 7. Ingbar, S. H. Clinical and physiological observations obtained. In the basal state, the increased TBG in a patient with an idiopathic decrease in the was associated with an increased PBI and a de- thyroxine-binding globulin of plasma. J. clin. In- creased proportion, but normal concentration, of vest. 1961, 40, 2053. free T4 in the serum. During two separate trials 8. Nicoloff, J. T., J. T. Dowling, and D. D. Patton. of diethylstilbestrol daily for 3 weeks, none of Inheritance of decreased thyroxine-binding by the these functions, including the TBG, changed sig- thyroxine-binding globulin. J. clin. Endocr. 1964, nificantly. During administration of norethan- 24, 294. and PBI 9. Scheinberg, I. H., and I. Sternlieb. metabo- drolone, in contrast, TBG decreased, lism. Pharmacol. Rev. 1960, 12, 355. the proportion of free T4 increased, but the con- 10. Sandberg, A. A., and W. R. Slaunwhite, Jr. Trans- centration of free T4-iodine remained normal. cortin: a corticosteroid-binding protein of plasma. In contrast to the findings with regard to TBG, II. Levels in various conditions and the effects of concentrations of ceruloplasmin and transcortin in estrogens. J. clin. Invest. 1959, 38, 1290. IDIOPATHIC INCREASE IN TBG 2271

11. Slaunwhite, W. R., Jr., and A. A. Sandberg. Trans- 18. Ingbar, S. H., L. E. Braverman, N. Dawber, and cortin: a corticosteroid-binding protein of plasma. G. Y. Lee. A simple method for measuring the J. clin. Invest. 1959, 38, 384. f ree thyroid hormone in serum. Clin. Res. 1964, 12. Sandberg, A. A., W. R. Slaunwhite, Jr., and A. C. 12, 271. Carter. Transcortin: a corticosteroid-binding 19. Benotti, J., and N. Benotti. Protein-bound iodine, protein of plasma. III. The effects of various total iodine, and butanol-extractable iodine by steroids. J. clin. Invest. 1960, 39, 1914. partial automation. Clin. Chem. 1963, 9, 408. 13. Mills, I. H., H. P. Schedl, P. S. Chen, Jr., and 20. Peterson, R. E., A. Karrer, and S. L. Guerra. F. C. Bartter. The effect of estrogen adminis- Evaluation of Silber-Porter procedure for de- tration on the metabolism and protein binding of termination of plasma hydrocortisone. Analyt. hydrocortisone. J. clin. Endocr. 1960, 20, 515. Chem. 1957, 29, 144. 14. Daughaday, W. H., R. E. Adler, I. K. Mariz, and 21. Scheinberg, I. H., and A. G. Morell. Exchange of D. C. Rasinski. Measurement of the binding ca- ceruloplasmin copper with ionic Cu' with refer- pacity of corticosteroid-binding globulin in hu- ence to Wilson's disease. J. clin. Invest. 1957, man plasma. J. clin. Endocr. 1962, 22, 704. 36, 1193. 15. Dowling, J. T., N. Freinkel, and S. H. Ingbar. 22. Peters, T., T. J. Biovanniello, L. Apt, and J. F. Ross. Thyroxine-binding by sera of pregnant women, A new method for the determination of serum newborn infants, and women with spontaneous abortion. J. clin. Invest. 1956, 35, 1263. iron-binding capacity. I. J. Lab. clin. Med. 1956, 16. Dowling, J. T., N. Freinkel, and S. H. Ingbar. 48, 274. Effect of diethylstilbestrol on the binding of thy- 23. Braverman, L. E., and S. H. Ingbar. Unpublished roxine in serum. J. clin. Endocr. 1956, 16, 1491. observations. 17. Robbins, J., and J. H. Nelson. Thyroxine-binding 24. Bothwell, T. H., and C. A. Finch. Plasma trans- by serum protein in pregnancy and in the newborn. ferrin and its iron in Iron Metabolism. Boston, J. clin. Invest. 1958, 37, 153. Little, Brown, 1962, p. 138.