Thyroid Function in Molar Pregnancy H. KOCK,1 H. v. KESSEL, L. STOLTE, AND H. V. LEUSDEN Department of Obstetrics and Gynecology, St. Radboud-Ziekenhuis, University of Nymegen, Netherlands

tion of the moles the PBI levels, BMR and resin uptakes returned to nonpregnant values, whereas the 131I-tracer test showed a sudden decrease in the thyroid secretion rate. These studies indicate that during molar pregnancy hyperfunction of the thyroid gland exists. It is suggested that this hyperfunction might be due to the production of a thyrotrophic substance by molar tissue. {J Clin Endocr 26:1128,1966)

ABSTRACT. Thyroid function was investigated in 6 patients with molar pregnancy by means of PBI 131 (all 6 patients), resin uptake (2 patients) and I-tracer test (1 patient). The PBI levels were found to be much higher than in normal pregnancies, whereas the resin uptakes were in the same range as those found in normal pregnancy. 13lI-tracer test showed a very high 131I uptake, conversion ratio and secretion rate during the molar pregnancy. After evacua-

T

HE CHANGES found in PBI, BMR, radioiodine uptake and conversion ratio during normal pregnancy are all compatible with increased thyroid activity. It is possible, however, to find other explanations for each of the changes which occurs. For instance, the increased PBI levels are said to be due to an increase in the thyroxine binding capacity of the serum proteins (1-4); the increased BMR to increased oxygen demands of the growing breast, uterus and the conceptus (5); and the increased uptake of 131I to an iodine depletion of the thyroid gland, secondary to an increased excretion of iodine in the urine (6). The changes in PBI, thyroxine binding capacity, 131I uptake and conversion ratio which occur during molar pregnancy are similar to the changes observed during a normal pregnancy, but to a more extreme degree (2, 7-9). This study was undertaken with the hope that these increased changes might afford the opportunity to clarify some causes of the changes observed in the indices of maternal thyroid function. In this report, we have presented the data of various investigations of thyroid function in six patients with hydatidiform mole.

Materials and Methods PBI levels were measured by the method of Barker (10). T3-131I resin uptakes were measured in the sera of 2 patients by the method of Woldring (11). HCG excretions were measured in 24-hr samples of urine with the quantitative Pregnosticon2 test, a modification of the hemagglutination reaction of Wide (12). With this method, dilutions of the samples under investigation are tested against a standard solution of HCG. The values given were for the most diluted solutions showing a positive reaction. The blood concentrations of HCG were measured semiquantitatively in mice using the method of Ascheim and Zondek (13). The estrogen excretion rate was measured in 24-hr urine samples by the method of Brown (14). Collection of these 24-hr urine samples was checked for completeness by creatinine content.131 A I-tracer test was performed in one patient for a period of 25 days, beginning 6 days before evacuation of the molar tissue and continuing for 19 days thereafter. We carried out this test without the use of medications to prevent 131I re-uptake because recent investigations have shown an increased TSH secretion resulting from administration of goitrogen (15). Thirty JUC of carrier-free m131 I was given orally, and for the next 4 days the I activity was measured in the 24-hr urine samples. On successive days, the 131 I content of the thyroid gland was estimated by measurements taken directly over the thyroid gland, using a sodium iodine scintillation counter3 with a wide angle lead collimator. The

Received November 1, 1965; accepted July 7, 1966. 1 Present address: Dept. Obstetrics and Gynecology, St. Canisius Ziekenhuis, Nymegen, Netherlands.

2 3

Pregnosticon Organon OSS, Netherlands. Philips Eindhoven, Netherlands.

1128

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THYROID FUNCTION IN MOLAR PREGNANCY

1129

crystal-to-skin distance was 30131cm. Protein- 25.8%), and uterus with marked changes in size bound radioiodine in plasma (PB I) was deter- on successive days. There were no signs of mined after precipitation of the plasma protein hyperthyroidism. The excretion of estrogens in with trichloroacetic acid and subseqent washing the 15th week of pregnancy was as follows: of the precipitate. Radioactivity in the urine estrone 214, estradiol 51, and estriol 147 ng/ and blood samples was counted in a Philips well- day (4 days after delivery these values were 24, type scintillation counter3 (background 98 13 and 19 /zg/day, respectively). During delivery cpm). Corrections were made with regard to and subsequent curettage, there was heavy loss background activity and physical decay of 131I. of blood, for which she was given a transfusion of 2 pints of blood. Unfortunately, the blood of one of the donors was heavily contaminated Case Reports with organic iodine, and thus the PBI values Patient 1 was a 20-yr-old woman, gravida after delivery were invalid. II, Para I, whose last menstrual period began on Patient 6 was a 28-yr-old woman, gravida II, 7/10/63. She complained of intermittent bleed- Para I. Her last menstrual period began on ing throughout pregnancy. In the 30th week, 4/18/63, and she subsequently complained of her blood pressure was 140/90, and the uterus vaginal bleeding, ptyalism, nausea and vomitwas smaller than anticipated from menstrual ing. Physical examination during the 12th week dates. There were no clinical signs of hyper- revealed blood pressure of 120/70, pulse rate of thyroidism. She spontaneously delivered a 120/min and marked dehydration. (Successive hydatidiform mole in the 31st week of preg- hemoglobin values during the 12th week were nancy. 14.4, 12.6, 10.0 g/100 ml, and in the 13th week, Patient 2 was a 27-yr-old woman, gravida 11.1 g/100 ml.) The uterus was far too large for III, Para II. Her last menstrual period was on the duration of the pregnancy. Renal function, 9/13/63. She complained of vaginal bleeding as judged by blood creatinine values of 4.5 and 6 throughout pregnancy, and when examined in mg/1 before and after delivery, was unremarkthe 19th week the uterus was found to be ex- able. There were no signs of hyperthyroidism. tremely large for the gestational age. Further The patient was treated with bed rest, and her physical findings were unremarkable. Three fluid balance was restored by intravenous infudays after this examination the patient under- sions of saline and glucose. In the 13th week, she went a curettage because of persistent bleeding. spontaneously delivered a hydatidiform mole, At this time, molar tissue and a fetus were and subsequently underwent a curettage. evacuted. Patient 3 was a 31-yr-old woman, gravida II, Results Para 0, whose first pregnancy was ectopic. After a normal menstrual period beginning 8/1/63, The data concerning PBI, resin uptake, she complained of intermittent vaginal bleed- BMR, HCG content and excretion of Paing. Initial physical examination was performed tients 1 to 5 are given in Table 1. These in the 17th week, with further examinations in 6 are given in Fig. 1, tothe 20th week. These revealed marked varia- values for Patient m tions in the size of the uterus. At the end of the gether with the I-tracer data. The serum 20th week of pregnancy, she spontaneously de- PBI levels of those patients with molar livered a hydatidiform mole. pregnancies were elevated to values found Patient 4 was an 18-yr-old primigravida during normal pregnancy (Table 2). In Pawhose last menstrual period began on 3/15/62. On her initial visit at 25 weeks of pregnancy tient 6, the very high concentration of PBI she complained of nausea, vomiting and vaginal may have been due partly to dehydration, bleeding. Physical examination revealed blood but, even after full hydration was achieved, pressure of 140/90, and uterus far too large for it was found to be higher than during northe gestational age. There were no signs of dehydration (hemoglobin 8.7 g/100 ml; Hct mal pregnancy. After delivery of the molar tissue, the 25.9%), or hyperthyroidism. She spontaneously delivered molar tissue in the 26th week of preg- PBI levels were found to decrease to values nancy. normal for nonpregnant adults (no. 4 and Patient 5 was a 19-yr-old primigravida. Her 6). last menstrual period began on 11/26/63, with The T3-131I resin uptake, done on the intermittent bleeding thereafter. Physical examination showed a blood pressure of 130/60, sera of Patients 2 and 3 during their molar marked anemia (hemoglobin 8.6 g/100 ml; Hct pregnancies, showed values well within the

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normal pregnancy range (11-17% of the dose). 13th week of pregnancy The excretion of HCG, determined in the 2 urine of Patients 1, 3, 4, 5 and 6 during PBI °i yug/100ml their molar pregnancies, was, as expected, lo^ far higher than for a normal pregnancy. In fTTI nn n accordance with this, the diluted sera of Patients 2, 4, 5 and 6 showed positive reBMR +40 sults with the Ascheim-Zondek test. The total excretion of estrogens in Pa+20 tients 5 and 6 was in the same range as that found by Brown (16) in normal pregnancy, 2.550 c = £(t) although the relationship between the quantities of estrone, estradiol and estriol 2.500; was not quite the same. The excretion of TV2 = 20d T'/2=104d estriol in our patients was slightly higher 2.450: than in normal pregnancies of the same I •-• U estriol duration. This higher estriol excretion is compatible with the results of MacDonald 400 et al. (17), who studied estrogen production 800 il_l 1 rates in molar pregnancies. — l_l estrone The summarized results of the 131I studies L 80 : are given in Fig. 1. They suggest an increased thyroid activity during pregnancy 160 as indicated by iodine uptake, intrathyestradiol roidal metabolism and thyroid secretion yug/24 hr 80 rate. Since no measures were taken to pre3 131 J M 1 Lhi r I re-uptake, it can be assumed vent the pregnosticon~4 111 |JJ1U - " - that this secretion U/24hr Jjj 5 rate was even higher _LU10 6 than the calculated ti/2 of 20 days (18). 7 10 After delivery of the mole, there was an inurine creatinine LLLLU crease in the 131I content of the thyroid, g/24 hr 1 2 indicating that over this period there was a curettage higher re-uptake than secretion of 131iodine. FIG. 1. Data concerning thyroid function, estrogen Ten days after delivery, the radioactivity and HCG excretion in Patient 6. c=f(t); c as a measured over the thyroid gland started to function of time, in which c= logarithm of the decrease (Fig. 1). From this decrease, we activity in cpm measured over the thyroid gland. calculated a ti/2 for the thyroidal secretion rate of 104 days. This is normal for nonpregTl /2 = biological half-life of the radioiodine in the nant adults. July 1963 10 15

20

25

August 30 1 5

l-LJ

MJ U

LJ_I

1fl

1 1 1

thyroid gland in which T is calculated from the equation Ct=coe~kt for first order reactions, in which Ct = concentration at time T; c0 = concentration at time zero; e = basis number for natural logarithms; k = constant. 131I tracer study: 24-hr 131 I uptake = 83% of the dose (normal 40-60%); neck/thigh ratio =818 (normal 60-120); PB1!»I after 72 hr = 1.00% of the dose A plasma (normal 0.05-0.20%).

Discussion PBI values in our six patients with molar pregnancies were found to be elevated to the levels reached in normal pregnancies. Studies carried out during the administration of estrogens to nonpregnant subjects indicate that the increase in concentration of circulating thyroid hormone results from

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THYROID FUNCTION IN MOLAR PREGNANCY

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TABLE 1. Laboratory data of Patients 1 through 5 (data concerning Patient 6 in Fig. 1) 1

2

Pregnant Pregnant

PBI 13l I-Ts Resin Uptake BMR HCG Urine: IU/24 hr HCG in Blood (A-Z)

Pregnant

Pregnant

After delivery

Pregnant

After delivery 1 week

31 weeks

weeks

17 weeks

20 weeks

26 weeks

1 week

13 weeks

15.6

15.4

8.2

12.1

16.3

7.0

17.2

—

16.9 —

11.5

11.8

—

1.2X106

1X105

4X104

4X103

1/200 pos.

—

—

1/400 pos.

—

5X106 —

19

20 +12

+7.5

a decrease in thyroxine turnover rate (19). This effect is brought about by the increase in thyroxine binding capacity of the serum proteins, which results from these heightened estrogen levels (20). As a result of these changes, there is a new equilibrium established in which the concentration of thyroxine in the serum is higher, but its turnover rate is lower, so that, in fact, the total daily thyroxine "utilization" remains unchanged (19). Despite the increased serum levels of PBI in pregnancy, the amount of free thyroxine is equal to (21, 22) or is even lower than that found in normal nonpregnant adults (4, 23). It is thought, therefore, that the increased concentration of serum PBI during uncomplicated pregnancy results from the same mechanism, i.e., increased thyroxine binding capacity. The fact that the resin uptake in two patients with molar pregnancies was in the range for normal pregnancy is compatible with a similar explanation for the elevated concentrations of serum PBI in molar pregnancy. However, values for estrogen excretion were only slightly different from those found during normal pregnancy. This suggests, therefore, that there is also another mechanism by which these extraordinarily high PBI concentrations were established. Furthermore, it should be noted that there is no definite proof that normal or low-normal free thyroxine concentrations indicate unchanged thyroid function. The normal or low-normal free

3.2X10 6 5.4X10 4 1/400 pos.

—

thyroxine concentration might indicate that the turnover rate of the increased extrathyroidal pool is decreased, but certainly it does not indicate that the total daily thyroxine utilization is unchanged. Figures on thyroxine utilization in healthy pregnant women are not available, but we found, in contrast to Dowling et al. (3), that thyroxine utilization increased during pregnancy in monkeys (24, 25). The 24-hour 131I uptake of 83% of the administered dose is indicative of an active thyroid gland as far as iodine uptake is concerned. This points either to a stimulated or to an iodine-depleted thyroid gland. The same holds true for the high PB131I concentration at 72 hours after the administration of 131I. The thyroid secretion rate was extremely high during this pregnancy. The ti/2 was 20 days, or, in other TABLE 2. PBI values during

uncomplicated pregnancies Duration of pregnancy weeks

'.No. of PBI pa- Mg/100 tients ml

3-7 8-11 12-15 16-19 20-23 24-27 28-31 32-35 36-40 1-2 weeks post partum 6 weeks post partum

2 14 13 8 15 21 22 27 35 47 15

6.8 7.7 7.6 7.7 8.0 8.0 7.8 8.4 8.3 7.5 5.7

SD

4.8 and 8.7 1.96 1.83 1.34 1.91 1.93 1.46 1.83 1.89 1.70 1.24

SD = Standard deviation.

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KOCK, KESSEL, STOLTE AND LEUSDEN

words, 3.46% of the total radioiodine content of the thyroid gland was lost per day. On the basis of indirect evidence (e.g., the PB131I concentration after 72 hr), it is commonly assumed that the radioactivity released from the thyroid is released as thyroid hormone (18, 26, 27). Further evidence is derived from the study of Goldsmith et al. (28), who demonstrated that the radioactivity released into the blood acted as hormonally bound radioactivity with regard to its binding to serum proteins, and, furthermore, had Rf values identical with those of T3 and T4. According to Werner and Block (29), and later confirmed by Wiener (30) in experiments with rats, this last finding is an artifact, due to a nonhomogeneous distribution of the radioiodine over the tyrosine and thyronine pools inside the thyroid gland. They suggested that the normal thyroid gland might release monoiodotyrosine and diiodotyrosine as well as T3 and T4 in equal quantities more or less. In the present study, therefore, it is assumed that the decrease in radioactivity over the thyroid gland is indicative of the secretion of thyroid hormone (s). Immediately following delivery, radioactivity over the thyroid increased, indicating that the re-uptake of inorganic 131I was higher than the secretion of mI-labeled hormone (s). This could have been caused by an increased re-uptake of radioiodine, a decreased secretion of labeled hormone (s), or by a combination of both. An increased re-uptake of 131I after delivery might be due to a change in maternal kidney function. This explanation is compatible with the findings of Aboul-Khair et al. (16) that during pregnancy the 131I excretion is higher than in the nonpregnant state. A decrease in the renal 131I excretion would, therefore, make more 131I available for re-uptake. Assuming that the re-uptake of radioiodine derived from the 131I-labeled thyroid hormone (s) degraded per day was about 80% (the initial 24-hr iodine uptake), and assuming that the amount of

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I-labeled thyroid hormone (s) degraded per 24 hours remained constant, it is, however, quantitatively impossible that even an increase in re-uptake to 100% could cause the observed increase in radioactivity measured over the thyroid gland. Therefore, increase in re-uptake might be a contributory factor, but certainly not the only explanation. Such an increase might be secondary to an increased degradation of labeled thyroid hormones after delivery. A rapid decrease in estrogens, with a concomitant decrease in the thyroxine binding proteins and, therefore, an increase in the concentration of "free" thyroxine, might be postulated to cause an increased utilization of thyroid hormone (s). This utilization would, of course, make more radioiodine available for re-uptake by the thyroid. However, this postulate is not supported by the data on estrogen excretion over the first 24 hours following delivery. Furthermore, this explanation assumes an extremely short halflife for the thyroxine binding proteins, since the change observed in thyroid secretion rate was so sudden. Unfortunately, the half-lives of the thyroxine binding proteins are unknown. The observations of Engstrom and Markhardt (31) indicate, however, that re-establishment of pretreatment PBI levels after cessation of estrogen therapy takes place in a matter of weeks rather than hours. This would make a high turnover rate of thyroxine binding proteins seem improbable. Moreover, in the experiments in which the influence of estrogen on the thyroid function was tested, there was either no change or only a slight increase in the thyroxine secretion rate after the administration of estrogens was discontinued (18, 32), whereas one would expect a decrease if our postulate were true. In order to explain the data of the present report it is neccessary to assume that following evacuation of the molar tissue there was a decrease primarily in the release of thyroid hormone (s) from the thyroid

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October 1966

THYROID FUNCTION IN MOLAR PREGNANCY

gland. This assumption is supported by the concomitant decrease in the concentration of PBI, although this may have been partly due to a decrease in the thyroxine binding capacity because of decreasing estrogen levels. To summarize, the high PBI concentrations and the normal values for resin uptake might indicate an increased thyroxine binding capacity of the serum proteins under the influence of estrogens. This does not explain, however, why the PBI values were so extraordinarily high, whereas the estrogen excretion was not appreciably different from estrogen excretion in normal pregnancies. The data of this 131I-tracer investigation cannot be explained solely on the basis of an iodine-depleted thyroid gland, since this is not in accordance with the sudden change in thyroid secretion rate at the time of delivery. The very high thyroid secretion rate (ti/2 20 days) during pregnancy indicates, therefore, a highly stimulated, rather than a severely iodinedepleted, thyroid gland. Since estrogens have either no effect or else an inhibiting effect on the thyroid function per se, we must assume that the thyroid gland of our patient during her molar pregnancy was stimulated by a factor other than estrogens, a factor that was eliminated with the delivery of the molar tissue. This appears to be the most satisfactory explanation for the very high PBI levels, the high 131I uptake, the high intrathyroidal metabolism and the high thyroid secretion rate during pregnancy, and this explanation also conforms to the sudden decrease in the thyroid secretion rate following delivery. The fact that none of our patients showed any clinical evidence of hyperthyroidism during their pregnancies cannot be regarded as evidence that this condition did not exist, since it is well known that gravidae are extremely tolerant of large doses of thyroid hormone. For instance, Fisher et al. (37) in their experiments on placental thyroxine transfer in humans used a dosage of

1133

500 to 8000 /xg Na-L-thyroxine intravenously without noting toxic reactions. Carr et al. (38) treated two patients throughout pregnancy with desiccated thyroid; one with a dose increasing from 3 to 28 grains/ day, and the second patient with a continuous dose of 20 grains/day, again without toxic reactions. Moreover, Engstrom et al. (33), Keynes (34), Schmid (35) and Benson et al. (36) all mentioned the fact that their hyperthyreotic patients improved clinically during pregnancy. The assumption of a thyrotrophin of chorionic origin may actually be proved; Odell et al. (39) reported a high TSH activity in the blood of two patients with choriocarcinoma. The fact that these investigators measured an even higher TSH activity in metastatic choriocarcinoma tissue makes a chorionic origin probable. HCG, present in high concentrations in both molar tissue and choriocarcinoma, proved to have no TSH activity in animal experiments (39, 40). The same is also indicated in our data by the gradual change in excretion of HCG shown in Fig. 1, while a sudden change is seen in the activity of the thyroid gland. It is difficult to say to what extent the changes in thyroid function during a molar pregnancy are comparable to the changes in thyroid function during normal pregnancy. Although the changing indices of thyroid function in molar pregnancy resemble those found in normal pregnancy, different physiological mechanisms may be involved. While there is no acceptable evidence that TSH activity is increased during normal pregnancy (41-43), this may well play a role in the increased thyroid function found in molar pregnancy. References 1. Dowling, J. T., S. H. Ingbar, and N. Freinkel, J Clin Endocr 19:1245,1959. 2. , Ibid., 20: 1, 1960. 3. Dowling, J. T., D. L. Hutchinson, W. R. Hindle, and C. R. Kleeman, J Clin Endocr 21: 779, 1961.

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4. Robbins, J., and J. H. Nelson, J Clin Invest 37: 153, 1958. 5. Hytten, F. E., and I. Leitch, The Physiology of Human Pregnancy, F. A. Davis Co., Philadelphia, 1964. 6. Aboul-Khair, S. A., J. Crooks, A. C. Turnbull, and F. E. Hytten, Clin Sci 27:195,1964. 7. Tisue, L., C. Stevenson, and J. Barzaletto, Abstract by C. H. Davis, The Thyroid Gland in Relation to Obstetrics and Gynecology, Gynec.-Obst., vol. 2, W. F. Prior Co., Inc., Hagerstown, Maryland, 1957, p. 11. 8. Singh, B. P., D. G. Morton, E. Krims, and J. Donley, Amer J Obstet Gynec 72: 607, 1956. 9. McKay, D. G., C. C. Roby, A. T. Hertig, and M. V. Richardson, Amer J Obstet Gynec 69: 722, 1955. 10. Barker, S. B., J Biol Chem 173: 715, 1948. 11. Woldring, M. G., H. Bakker, and H. Doorenbos, Ada Endocr (Kobenhavn) 37: 607, 1961. 12. Wide, L., and C. A. Gemzell, Ada Endocr (Kobenhavn) 35: 261,1960. 13. Ascheim, S., Die Schwangerschaftsdiagnose aus dem Harne, Karger, Berlin, 1930. 14. Brown, J. B., BiochemJ 60:185,1955. 15. Morreale de Escobar, G., and F. Escobar del Rey, Endocrinology 71: 906,1962. 16. Brown, J. B., Lancet 1: 704, 1956. 17. MacDonald, P. C , and P. K. Siiteri, J Clin Endocr 24: 685,1964. 18. Solomon, D. H., Metabolism 5: 667,1956. 19. Dowling, J. T., N. Freinkel, and S. H. Ingbar, Program of Annual Meeting of the American Goiter Association, San Francisco, Calif., June 17-19, 1958 (Abstract 12): 20. Engbring, N. H., and W. W. Engstrom, J Clin Endocr 19: 783,1959. 21. Christensen, L. K., Endocrinology 66: 138, 1960. 22. Osorio, C , D. J. Jackson, J. M. Gartside, and A. W. G. Goolden, Clin Sci 23: 525,1962. 23. Sterling, K., and A. Hegedus, J Clin Invest 4 1 : 1031, 1962.

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24. Kock, H. C , Schildklier en Zwangerschap, Thesis, Nymegen, Netherlands, 1965. 25. Stolte, L., H. Kock, H. van Kessel, and L. Kock, Ada Endocr (Kobenhavn) 52: 383, 1966. 26. Goldsmith, R. E., J. B. Stanbury, and G. L. Brownwell, J Clin Endocr 11:1079,1951. 27. Einhorn, J., and L. G. Larson, J Clin Endocr 19: 33, 1959. 28. Goldsmith, R. E., C. Herbert, and G. Lutch, J Clin Endocr 18: 367, 1958. 29. Werner, S. C , and R. J. Block, Nature (London) 183: 406,1959. 30. Wiener, J. D., Abstract of Lecture at Med. Biol. Fed. Verg., Utrecht, Netherlands, 1964. 31. Engstrom, W. W., and B. Markhardt, J Clin Endocr 14: 215,1954. 32. Brown-Grant, K., Ciba Foundation Colloquia on Endocrinology 10: 97,1957. 33. Engstrom, W. W., D. M. Kydd, J. P. Peters, and E. B. Man, J Clin Invest 30:151,1951. 34. Keynes, G., J Obstet Gynaec Brit Emp 59: 173, 1952. 35. Schmid, H. H., Arztliche Wochenschrift 11: 46, 1005, 1956. 36. Benson, R. C , D. E. Pickering, N. E. Kontaxis, and D. A. Fisher, Obstet Gynec 14: 11, 1959. 37. Fisher, D. A., H. Lehman, and C. Lackey, J Clin Endocr 24: 393,1964. 38. Carr, E. A., W. H. Beierwaltes, G. Raman, V. N. Dodson, J. Tanton, J. S. Betts, and R. A. Stambaugh, J Clin Endocr 19:1,1959. 39. Odell, W. D., R. W. Bates, R. S. Rivlen, M. B. Lipsett, and R. Hertz, J Clin Endocr 23: 658, 1963. 40. Fitko, R., Ada Physiol Pol, 1963 (Abstract). 41. Yamazaki, E., A. Noguchi, and D. W. Slingerland, J Clin Endocr 21:1013,1961. 42. Ueda, Y., M. Mochizuki, Y. Kishimoto, T. Washio, S. Mizusawa, and O. Ishigama, Endocr Jap 11: 67, 1964. 43. Greer, M. A., Endocrinology 45:178,1949.

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