[Screening for congenital hypothyroidism]

In the Netherlands nation-wide screening for CH began in January 1981. The aim of the combined T4-TSH screening method is to detect all forms of CH, primary as well as secondary and tertiary. More than 99% of the newborns are screened. The rate of false-positives in premature infants was reduced in June 1982 by a change of the indications for follow-up. Further study is performed on T4 values of premature infants. The information, given to the parents in case of recall, is not optimal yet. Although there is still delay in screening and follow-up, the initiation of treatment is considerably advanced. The effect of earlier treatment on development will be assessed by Prof. Dr. A. F. Kalverboer. Very likely, the early treatment will lead to a considerable reduction of damage to the central nervous system.

The transition from a fixed ratio to a fixed interval schedule of reinforcement in hypo and hyperthyroid rats

The modification of behavior caused by hypo and hyperthyroidism were studied when the schedule of reinforcement was changed from a fixed ratio to a fixed interval. The conditions of hypo and hyperthyroidism were obtained with a chronic administration of methimazole and of 1-thyroxine. The level of the modifications of thyroid activity was determined by evaluation of the basal metabolic rate and of the plasma levels of T4. Hyperthyroidism caused no modification of the rat behaviour. A difficulty in adapting to the new experimental situation (learning) was found in hypothyroidism. This effect is evident in high hypothyroidism. In low hypothyroidism a depression of the rat behaviour may interfere with the modification of the learning process.

Behavioral testing of progenies of Tx (hypothyroid) and growth hormone-treated Tx rats: an animal model for mental retardation

Virgin Sprague-Dawley Holtzman rats were rendered Tx (hypothyroid) by radiothyroidectomy and maintained on 1.0 microgram T4 (thyroxine) per 100 g BW until pregnant. One-half of these Tx animals were administered 0.5 IU of growth hormone (GH) during the last 10-11 days of gestation as GH secretion is especially deficient in Tx rats. Untreated, food restricted to the level consumed by the Tx-only rats, GH-treated euthyroid, and T4-treated until pregnant animals served as controls. The animals were allowed to go through parturition and each litter was reduced to no more than 6 pups by removing pups for tissue weights and protein analyses at 1 and 5 days of age. The pups were weaned at 22 days of age and 2 animals per litter were utilized for behavioral testing between 40 and 60 days of age. At the end of the behavioral testing period the 60-day-old offspring were sacrificed to obtain tissue weights and protein concentrations. The behavioral tests were based on the ability of the animals to learn a Lashley's type 3 enclosed alley maze and their spontaneous activity was measured in stabilimeter cages. The animals were fasted overnight on alternate days and then given a food reward upon traversing the maze. This allowed for 10 separate trials in both the Lashley maze and the stabilimeters over the 20-day period from 40 to 60 days of age. Our previous studies have shown the fetuses and progenies of Tx-only mothers to have multiple metabolic defects including reduced rates of protein synthesis and tissue protein concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Modification of the behavioural effects of haloperidol and of dopamine receptor regulation by altered thyroid status

Rats made hypothyroid by the chronic oral administration of 200 mg/kg propylthiouracil were less sensitive to the cataleptic effects of haloperidol (0.1 mg/kg) treatment than were euthyroid rats chronically treated with isotonic saline. However, rats made hyperthyroid by the chronic injection of 200 micrograms/kg thyroxine were not more sensitive to the cataleptic suppressant effects of haloperidol (0.1 mg/kg). Higher doses of haloperidol (1 and 5 mg/kg) produced significantly greater catalepsy in the hyperthyroid rats and significantly reduced catalepsy in the hypothyroid rats. Receptor binding studies carried out on the striata from rats sacrificed 48 h after a 6-day course of chronic haloperidol (0.1 mg/kg once daily) treatment revealed a significant upregulation (increase) of dopamine receptors in the hypothyroid rats only. These findings are consistent with the hypothesis that altered thyroid status can modify the sensitivity of dopamine receptors.

The development of children with congenital hypothyroidism

Standardised motor, intellectual and behavioural tests were undertaken in a group of 56 children in the north of England. All were aged between five years and 15 years 11 months and all had congenital hypothyroidism. The results were compared with those of a control group. The mean IQ of the hypothyroid group was found to be 1 to 2 standard deviations below the population mean. In the group there was no correlation between developmental measures and age at diagnosis but in a subgroup with bone-age evidence of prenatal hypothyroidism there was a correlation between age at diagnosis and both intellectual and motor development. Intellectual development was normal among those treated before one month of age, but there was some evidence of disturbed fine motor and cerebellar functions.

Biochemical victims: false negative diagnosis through overreliance on laboratory results--a personal report

The increasing tendency of doctors to base diagnosis on the results of laboratory investigations entails a corresponding decrease in the exercise of clinical judgment. This state of affairs can have harmful consequences for patients suffering from biochemically atypical forms of disorder, who may acquire functional psychiatric labels when they are in fact suffering from organic physical disorders. The author's personal experience of this invidious predicament is described. Although hypothyroidism was correctly diagnosed on clinical grounds within a few months of presentation, laboratory results were inconclusive and three years and three specialist consultations were to elapse before replacement therapy was obtained, and then only through unofficial channels. The handling of this case illustrates some unfortunate trends in contemporary medical practice with important implications for the health of patients.

Preliminary results on the mental development of hypothyroid infants detected by the Quebec Screening Program

A prospective study of the mental development of hypothyroid infants detected by the Quebec Network for Genetic Medicine began in January, 1976. The mean age at initiation of thyroid hormone therapy was 27 days. Forty-five hypothyroid infants and 37 normal control subjects were assessed at age 12 months with the Griffiths mental development test; 77 and 41, respectively, were assessed at age 18 months, and 59 and 40, respectively, at 36 months. There were no statistically significant differences in the various test scores between the two populations at age 12 months, but at age 18 and 36 months the hypothyroid infants had lower scores in hearing-speech performance scales and practical reasoning (36 months) which also decreased their global quotient. The mean scores were still above 100 and only nine were below 85. Further assessment of the influence of early therapy on mental development at age 6 years is needed before definitive statements can be made about the long-term mental development in these subjects.

Psychological reactions in 102 families with a newborn who has a falsely positive screening test for congenital hypothyroidism

The potential psychological risks of falsely positive test results in neonatal screenings have not been studied previously. 20 000 newborns were screened for congenital hypothyroidism. Of the 144 positive tests, 137 were false. The families of 102 babies with false positives were explored in reference to their (1) initial parental psychic reactions (emotional reactions and abilities for coping) and (2) residual reactions 6 to 12 months later. 78 families initially exhibited strong emotional reactions. Providing information about a positive screening test is therefore an acute strain to the majority. After a period of 6 to 12 months there was in 18 families persistent insecurity regarding the baby's health. These concerns were linked to the family to the screening and the disease screened for. This may impair the parent-child relation and thus, the child's development. Thus a false positive test appear to trigger in the majority a development of a psychic crisis. 12 families seemed however to have been totally untouched by the potential threat of the information. The crisis is effectively solved by most (consideration must be paid to the integrated psychological support given to all). It is not known whether the 18 risk families actually have been iatrogenically hurt or if their worries brought to attention in connection with the screening merely represent habitual psychic maladjustment. Preparation for parenthood and education about screening principles are beneficial and important. This study demonstrates the importance not only of asking how much worry is elicited but also how this worry is being handled (coping ability) in order to provide a fair estimate as to which families are at risk.

Congenital hypothyroidism in Sweden. Psychomotor development in patients detected by clinical signs and symptoms

Thirty-nine children at 7 to 9 years of age with congenital hypothyroidism have been studied with respect to their intellectual, neurological and social functions. Their intellectual achievement as assessed by the WISC test, was significantly lower than in a reference population (mean IQ 88, range 50-113). In children who showed signs and symptoms of hypothyroidism during their first four weeks of life, there was a negative correlation between the age when therapy was started and intellectual development. No such correlation was found in children who showed signs and symptoms after the first four weeks of life. Nine children of 26 with signs of hypothyroidism in the neonatal period, were found to have neurological abnormalities consisting of fine and gross motor disturbances. The neurological abnormalities seriously affected daily life in only the two most severely mentally retarded. No correlation was found between the age when the therapy was started and neurological abnormalities. Three children attended special schools because of mental retardation and six attended normal schools but required additional teaching assistance for learning disabilities. Our results suggest that the risk of future intellectual handicaps may be reduced by early treatment in children with hypothyroidism presenting during the neonatal period.

Psychiatric presentations of hypothyroidism

Hypothyroidism can often be misdiagnosed as psychiatric illness. The hypothyroid patient may present with depression, an organic mental disorder, apathy and/or frank psychosis (usually with paranoid symptoms). Psychiatric manifestations of the endocrinopathy will abate with thyroid hormone replacement therapy, unless the disease state has been sufficiently prolonged to cause some irreversible brain damage. This irreversibility mandates prompt diagnosis and specific hormonal replacement therapy. Thus, thyroid function screening is recommended for patients presenting with depression, psychosis or organic mental disorder.

Intellectual, school and occupational performance in patients with idiopathic hypothalamo-pituitary hypothyroidism and primary hypothyroidism

Intelligence quotient (IQ), school and professional performance were reviewed in 33 patients with idiopathic hypothalamo-pituitary hypothyroidism. Diagnosis was based on low T4 values and clinical signs. All were treated with growth hormone (HGH). In some, hypothyroidism became manifest only after HGH therapy. Birth history revealed breech delivery in 24 and perinatal asphyxia in 15 of them. Thyroid treatment was started at a mean age of 9.8 (range 4-18 years). The mean IQ was 103.4 +/- 16.7 (SD). 9 patients had IQs below 90, 8 of them were born by breech delivery, 3 had severe perinatal asphyxia, one recurrent symptomatic hypoglycemia, and one a micropenis. Of those patients who have reached the respective age, 7 attended college, 3 university, and 9 had skilled professions. Only 7 required special education. For comparison, 52 patients with primary hypothyroidism were studied. Their mean IQ was with 89.3 +/- 18.1 (SD) significantly lower (p < 0.001) than the mean IQ of patients with hypothalamo-pituitary hypothyroidism. The best IQ (96.8 +/- 16.9) was attained when thyroid treatment was started before the age of 4 months, the lowest IQ (78.2 +/- 19.2) was found in the group of patients in whom thyroid substitution was initiated between 5 and 12 months. Patients who were treated after one year of age, had a mean IQ of 90.0 +/- 15.7. This group includes patients with ectopic thyroid glands or acquired hypothyroidism such as Hashimoto's thyroiditis.

Thyroid-induced mania in hypothyroid patients

This retrospective study, based on 18 case reports, describes an organic affective syndrome, manic type, occurring shortly after the initiation of thyroid replacement in hypothyroid patients. The symptomatology and homogeneity of the syndrome offers insight into the relationship between thyroid activity and affective disturbance. The patients experiencing mania showed concurrent psychopathology at the time of replacement therapy, frequently had a past history of personal or familial psychiatric disorder and were given dosages in the high range of normal. The potential morbidity of the manic state was considerable. These findings suggest that a group of hypothyroid patients at risk can be identified. In such a group, lower initial dosages and gradual increases in dosage may be indicated.

Development of olfactory and thermal responsiveness in hypothyroid and hyperthyroid rat pups

Hypo- and hyperthyroid rat pups were tested for their responsiveness on an olfactory and a thermal gradient in an attempt to evaluate the effects of perinatal thyroid manipulation on the ability of the pups to use these cues in orientation. Hypothyroid pups showed a delay and hyperthyroid pups an acceleration in the development of orientation along the olfactory gradient, relative to controls. None of the pups was able to utilize a thermal gradient in directed orientation but pups moved less at the warm end of the gradient than at the cool end. This differential responsiveness was strongest in the hypothyroid pups, suggesting that these pups could utilize thermal cues in an orthokinetic orientation.

Development of home orientation in hypothyroid and hyperthyroid rat pups

In order to assess the effects of perinatal hypothyroidism or hyperthyroidism on the development of an integrated behavioral response, we tested hypothyroid, hyperthyroid, and control pups, as well as pups receiving thyroxine replacement therapy, for the development of the home orientation response. Hypothyroidism was induced in the pups by feeding the pregnant or lactating female a diet of .2% propylthiouracil from Day 15 of gestation to Day 22 postpartum. Pups receiving replacement therapy and pups made hyperthyroid were injected daily with thyroxine, starting at birth. The ability of the pups to initiate and maintain locomotion toward the nest was assessed between Days 4 and 22. Hyperthyroid, control, and replacement therapy pups behaved very similarly on the task, showing a peak in the percentage of pups homing between Days 12 and 16. Hypothyroid pups showed a delay in the peak percentage until Day 20, although the percentage of pups was similar to that found in other treatments. An integrated behavioral response can be delayed by hypothyroidism and still emerge apparently intact at a later age.