A Survey of the Current Methods Used in the UK to Assess Pituitary Function

Comparing the utility of 30- and 60-minute cortisol levels after the standard short synacthen test to determine adrenal insufficiency: A retrospective cross-sectional study

Short Synacthen test (SST) involves measuring the baseline, 30-, and 60-minute serum cortisol levels, after injecting 250 μg of synthetic adrenocorticotropic hormone or Synacthen (ACTH). This study aimed to review the current clinical practice of performing SST to establish a standardized test protocol and to additionally test the hypothesis regarding performing the 60-minute cortisol test alone and the dependence of overall SST result on baseline cortisol level.Patients >14 years who underwent SST from January 2010 to December 2017 were included. Pearson's chi-square cross-tabulation was used to identify individuals with inconsistent 30- and 60-minute serum cortisol test results. Logistic regression analysis was performed to predict normal responses based on the baseline cortisol value.Of the 965 patients identified from pharmacy, medical, and laboratory records, 849 were included. Mean baseline, 30-, and 60-minute cortisol levels after ACTH injection were 394 ± 286.58, 722 ± 327.11, and 827 ± 369.30 nmol/L, respectively. Overall, 715 (84%) and 134 (16%) patients had normal and abnormal responses, respectively. Primary and secondary adrenal insufficiency was diagnosed in 10% and 35%, respectively, while ACTH levels were not measured in 55% of the patients. Overall, 9.49% (n = 72) of the patients had a suboptimal response at 30 minutes, but reached the threshold value of 550 nmol/L at 60 minutes. This particular subgroup's mean change (240 nmol/L) in cortisol level from baseline to 30-minute was higher than that observed in patients with abnormal response at both time-points (mean change, 152 nmol/L). No patient with 30-minute optimal responses had 60-minute suboptimal responses. The baseline serum cortisol threshold of ≥226 nmol/L had 80% sensitivity, 71% specificity, and 93% positive predictive value for detecting a normal SST (P-value < .0001).Relying on a 60-minute cortisol level can identify all normal and abnormal responses, while relying on 30-minute cortisol level alone may produce false-positives. Additionally, a baseline cortisol level of ≥226 nmol/L is a reliable threshold for determining adequate adrenal function, particularly with a low pretest hypoadrenalism probability.

Do we need 30 min cortisol measurement in the short synacthen test: a retrospective study

OBJECTIVE

The short synacthen test (SST) is widely used across the UK to assess adrenal reserve but there remains no consensus on the timing of cortisol sampling to help diagnose adrenal insufficiency. The main objective of our study was to see if both 30 and 60 min sample are required following administration of synacthen to investigate suspected adrenal insufficiency (AI).

DESIGN

This was a single-centre retrospective study of 393 SSTs measuring 0, 30 and 60 min cortisol levels after administration of 250 µg of synacthen.

PATIENTS AND METHODS

All the SSTs for patients suspected of primary or secondary AI between April 2016 and October 2018 were included in this study. The tests were performed as per our hospital protocol. A post-adrenocorticotropic hormone (ACTH) cortisol response of 420 nmol/L at any time point was considered adequate to rule out AI. The data were analysed to ascertain the proportion of patients who achieved this level at 30 and/or 60 min.

RESULTS

A total of 393 SST results were included in this study. Patients were divided into two groups depending on whether (group A) or not (group B) they were on steroids. Overall, a total of 313 (79.6%) subjects achieved cortisol level of ≥420 nmol/L at 30 and 60 min while 19 (4.8%) had late response (ie, insufficient 30 min cortisol levels, rising to ≥420 nmol/L at 60 min). Another 61 subjects (15.5%) showed insufficient response at both 30 and 60 min (ie, failed to achieved level of ≥420 nmol/L). Importantly, there was no patient in either group who had adequate response at 30 min and then failed at 60 min. Patients in group A were more likely to have inadequate response at both 30 and 60 min while patients in group B were more likely to have normal response at both time points.

CONCLUSIONS

Our results suggest that about 5% of people undergoing SST may be inappropriately diagnosed as having AI (and subjected to long-term unnecessary steroid treatment) if the 60 min sample is not maintained. We suggest that 30 min sample does not add any additional diagnostic utility and can be omitted thus simplifying SST even further and saving on cost and resources. We propose that single measurement after 60 min of administration of synthetic ACTH is a sufficient screening test for AI.

Renal Papillary Rarefaction: An Artifact Mimicking Papillary Necrosis

In histopathology, the presence of a tissue change that does not represent the tissue's normal appearance can often lead to an incorrect diagnosis and interpretation. These changes are collectively known as "artifacts" resulting from postmortem autolysis, improper fixation, problems with tissue handling or slide preparation procedures. Most tissue artifacts are obvious, yet some artifacts may be subtle, occur in relatively well-fixed tissue, and demand careful observation to avoid confusion with real biological lesions. The kidney often contains artifacts that may be observed throughout all regions of the renal parenchyma. Cortical tubule artifacts present the greatest challenge when discerning an artifact versus an induced lesion following exposure to a xenobiotic. However, confounding artifacts observed at the tip of the renal papilla may also be problematic for the pathologist. An uncommon artifact involving tinctorial alteration and rarefaction affecting the papillary tip of the rat kidney is described here and differentiated from treatment induced lesions of renal papillary necrosis.

International survey on high- and low-dose synacthen test and assessment of accuracy in preparing low-dose synacthen

OBJECTIVE

The short synacthen test (SST) is widely used to assess patients for adrenal insufficiency, but the frequency and protocols used across different centres for the low-dose test (LDT) are unknown. This study aimed to survey centres and test the accuracy of ten different synacthen preparation strategies used for the LDT.

METHODS

Members of 6 international endocrine societies were surveyed regarding diagnostic tests used for adrenal insufficiency, and in particular the SST. Synacthen was diluted for the LDT and concentrations measured using a synacthen ELISA.

RESULTS

Survey responses were received from 766 individuals across 60 countries (52% adult, 45% paediatric endocrinologists). The SST is used by 98% of centres: 92% using high-dose (250 μg), 43% low-dose and 37% both. Ten low-dose dilution methods were assessed and variation in synacthen concentration was demonstrated with intramethod coefficients of variation (CV) ranging from 2.1% to 109%. The method using 5% dextrose as a diluent was the least variable (CV of 2.1%). The variation in dilution methods means that the dose of synacthen administered in a LDT may vary between 0.16 and 0.81 μg.

CONCLUSIONS

The high-dose SST is the most popular diagnostic test of adrenal insufficiency, but up to 72% of paediatric endocrinologists use a LDT. There is considerable variation observed both within and between low-dose synacthen dilution methods creating considerable risk of inaccurate dosing and thereby invalid results.

Chronic hypopituitarism is uncommon in survivors of aneurysmal subarachnoid haemorrhage

OBJECTIVE

The incidence of hypopituitarism after aneurysmal subarachnoid haemorrhage (SAH) is unclear from the conflicting reports in the literature. As routine neuroendocrine screening for hypopituitarism for all patients would be costly and logistically difficult, there is a need for precise data on the frequency of hypopituitarism and on factors which might predict the later development of pituitary dysfunction. We aimed to: (i) Establish the incidence of long-term hypopituitarism in patients with aneurysmal SAH. (ii) Determine whether data from patients' acute admission with SAH could predict the occurrence of long-term hypopituitarism.

DESIGN

One hundred patients were studied prospectively from the time of presentation with acute SAH. Plasma cortisol, plasma sodium and a variety of clinical and haemodynamic parameters were sequentially measured for the first 12 days of their acute admission. Forty-one patients then underwent dynamic pituitary testing at median 15 months following SAH (range 7-30 months), with insulin tolerance test (ITT) or, if contraindicated, a glucagon stimulation test (GST) plus short synacthen test (SST). If symptoms of cranial diabetes insipidus (CDI) were present, a water deprivation test was also performed.

RESULTS

Forty-one patients attended for follow-up dynamic pituitary testing. Although 14 of 100 had acute glucocorticoid deficiency immediately following SAH, only two of 41 had long-term adrenocorticotrophic hormone (ACTH) deficiency and four of 41 had growth hormone (GH) deficiency. None were hypothyroid or gonadotrophin deficient. None had chronic CDI or hyponatraemia. There was no association between acute glucocorticoid deficiency, acute CDI or acute hyponatraemia and long-term pituitary dysfunction.

CONCLUSION

Both anterior and posterior hypopituitarism are very uncommon following SAH and are not predicted by acute clinical, haemodynamic or endocrinological parameters. Routine neuroendocrine screening is not justified in SAH patients.

Determining the utility of the 60 min cortisol measurement in the short synacthen test

OBJECTIVE

Despite the widespread use of the short synacthen test (SST), there remains no clear consensus on sampling times for the measurement of serum cortisol that best determines adrenal reserve. We set out to establish whether there is any value in measuring serum cortisol at 60 min following administration of synacthen.

DESIGN

Retrospective data analysis of 500 SST results measuring 0, 30 and 60 min cortisol levels after administration of 250 μg of synacthen at 2 large urban National Health Teaching Hospitals in the UK.

PATIENTS AND MEASUREMENTS

Individuals thought to have primary or secondary adrenal insufficiency given 250 μg of synacthen.

MEASUREMENTS

Serum cortisol levels measured at 0, 30 and 60 min, looking to see how many people who had adrenal insufficiency at the 30 min sample but in whom the 60 min sample showed adequate adrenal reserve.

RESULTS

The results from 384 people were analysed. A total of 276 had normal responses at 30 min and also at 60 min. A sum of 33 individuals had 'insufficient' (i.e., <550 nmol/l) 30 min cortisol levels, rising to ≥ 550 nmol/l at the 60 min test. All 75 individuals who were insufficient at 60 min were also insufficient at 30 min. No individuals passed (≥550 nmol/l) at 30 min and then failed (<550 nmol/l) at 60 min.

CONCLUSIONS

These results suggest that a significant proportion of people undergoing a SST may be inappropriately diagnosed as having adrenal insufficiency if the 60 min sample is not measured. We suggest that the 60 min sample is measured in all individuals having a SST to prevent unnecessary over-diagnosis of adrenal insufficiency.

Assessing the HPA axis in patients with pituitary disease: a UK survey

OBJECTIVE

Assessing the integrity of the hypothalamic-pituitary-adrenal (HPA) axis following pituitary surgery is necessary to determine the requirement for glucocorticoid replacement therapy, but there remains controversy about the optimum way to measure this.

DESIGN AND MEASUREMENTS

Postal questionnaire survey among UK endocrinologists to evaluate the current methods used.

RESULTS

The response rate was low (81 out of 598 questionnaires mailed), although 85% were consultants. Fifty-five percent measured 9:00 h plasma cortisol in the immediate postoperative phase. Most carried out definitive testing between 4 and 12 weeks: 36% routinely used the insulin tolerance test (ITT), 59% used the short synacthen test (SST). The 30-min cortisol value was used by 67% as a 'pass' when interpreting the results. Others included cortisol measurement at 60 min (17%) or incremental value (7%). For long-term follow-up of patients not rendered ACTH-deficient by surgery, 64% used the SST for patients who had received radiotherapy. If patients had not had radiotherapy, 42% used the SST, whereas 33% did no routine testing unless the patient was symptomatic or there was evidence of tumour recurrence on imaging. If patients were symptomless but 'failed' the chosen test, 28% still treated the patient with glucocorticoid replacement, 38% retested before treatment and 24% recommended glucocorticoid cover for when unwell or 'stressed'. Fifty-six percent used hydrocortisone at doses of 20 mg/day as replacement therapy.

CONCLUSION

Thus, assessment of the HPA axis remains controversial. Although the SST is becoming more popular, there is still considerable variation in the interpretation of results and, in particular, the decision of whether or not to treat with lifelong glucocorticoid replacement therapy.

The TSH response to domperidone reflects the biological activity of prolactin in macroprolactinaemia and hyperprolactinaemia

OBJECTIVE

To test the hypothesis that patients with hyperprolactinaemia due to biologically inactive macroprolactin will not show the characteristically increased dopaminergic inhibition of TSH release seen in patients with microprolactinomas secreting biologically active monomeric PRL.

DESIGN

Comparison of the TSH and PRL responses to dopamine antagonism with domperidone (10 mg i.v.) in patients with hyperprolactinaemia due to macroprolactinaemia or microprolactinomas.

PATIENTS

Twenty-two patients referred for the investigation of their hyperprolactinaemia were studied: 11 patients with macroprolactinaemia and 11 patients with hyperprolactinaemia due to microprolactinoma.

MEASUREMENTS

TSH and PRL levels were measured at baseline and 30 min following domperidone in both groups.

RESULTS

Patients with macroprolactinaemia showed normal TSH and PRL responses to dopamine antagonism whereas patients with microprolactinomas showed exaggerated TSH responses and reduced PRL responses. Although there was considerable overlap between the PRL responses in the two groups, there was very clear separation between the PRL/TSH response ratios (normal > 1.0) of 4.0 +/- 1.8 for the macroprolactinaemia group and 0.4 +/- 0.2 for the microprolactinoma group (P < 0.0001).

CONCLUSIONS

These data support the hypothesis that elevated circulating levels of macroprolactin, as opposed to biologically active monomeric PRL, do not exert increased positive feedback on the hypothalamic dopaminergic inhibition of TSH release.

Ten years on: Safety of short synacthen tests in assessing adrenocorticotropin deficiency in clinical practice

Since 1988, when a retrospective study of patients attending this unit was published, we have advocated the use of the short synacthen test (SST) as the primary screening investigation to detect ACTH deficiency. However, others have published comparisons of SST and insulin tolerance tests that suggest a significant false negative rate with SST, leading to concern that some patients who pass the SST are in danger from the clinical consequences of ACTH deficiency. To address this, we audited biochemical results and clinical outcome in 63 patients who did not have ACTH deficiency detected (i.e. who passed the test) by SST after pituitary surgery. Twelve of the 63 patients who passed a SST after pituitary surgery became ACTH-deficient later as diagnosed by SST: 4 within the first year, 2 of whom had received postoperative radiotherapy (3 had symptoms of tiredness and 1 was admitted to the hospital with a viral infection); 8 in yr 3-5, 7 of whom had received postoperative radiotherapy (all had either no symptoms or symptoms of tiredness alone). Thus, the predictive value of the SST in excluding ACTH deficiency is approximately 97% (2 of 63 patients who initially passed the SST were found to be ACTH-deficient within 12 months without having received postoperative radiotherapy). Only 1 patient was ill enough to require hospital admission. Setting the risk of false negatives with SST against the morbidity and manpower implications associated with insulin tolerance tests, SST remains the primary screening test for ACTH deficiency in our practice. However, a high index of clinical suspicion to detect false negative results must be maintained.

Adrenocorticotropin stimulation tests in patients with hypothalamic-pituitary disease: low dose, standard high dose and 8-h infusion tests

OBJECTIVES

Low doses of ACTH [1-24] (0.1, 0.5 and 1.0 microg per 1.73 m2) may provide a more physiological level of adrenal stimulation than the standard 250 microg test, but not all studies have concluded that the 1.0 microg is a more sensitive screening test for central hypoadrenalism. Eight-hour infusions of high dose ACTH [1-24] have also been suggested as a means of assessing the adrenals' capacity for sustained cortisol secretion. In this study, we compared the diagnostic accuracy of three low dose ACTH tests (LDTs) and the 8-h infusion with the standard 250 microg test (HDT) and the insulin hypoglycaemia test (IHT) in patients with hypothalamic-pituitary disease.

SUBJECTS AND DESIGN

Three groups of subjects were studied. A healthy control group (group 1, n = 9) and 33 patients with known hypothalamic or pituitary disease who were divided into group 2 (n = 12, underwent IHT) and group 3 (n = 21, IHT contraindicated). Six different tests were performed: a standard IHT (0.15 U/kg soluble insulin); a 60-minute 250 microg HDT; three different LDTs using 0.1 microg, 0.5 microg and 1.0 microg (all per 1.73 m2); and an 8-h infusion test (250 microg ACTH [1-24] at a constant rate over 8 h).

RESULTS

Nine out of the 12 patients in group 2 failed the IHT. Three out of 12 patients from group 2 who clearly passed the IHT, also passed all the ACTH [1-24] stimulation tests. Seven of the 9 patients who failed the IHT, failed by a clear margin (peak cortisol < 85% of the lowest normal). Two of the 7 also failed all the ACTH [1-24] tests. Five of the 7 patients had discordant results, four passed the 0.1 LDT, one (out of four) passed the 0.5 LDT, none (out of three) passed the 1.0 LDT, two passed the HDT and three passed the 8-h test. Two patients were regarded as borderline fails in the IHT. Both passed the ACTH [1-24] tests, although one was a borderline pass in the 8-h test. Only five out of the 21 patients in group 3 showed discordance between the HDT and the LDTs. One patient passed the HDT and failed the 0.1 LDT, four patients failed the HDT but passed some of the different LDTS.

CONCLUSIONS

We conclude that in the diagnosis of central hypoadrenalism, ACTH [1-24] stimulation tests may give misleading results compared to the IHT. The use of low bolus doses of ACTH [1-24] (1.0, 0.5 or 0.1 microg) or a high dose prolonged infusion does not greatly improve the sensitivity of ACTH [1-24] testing. Dynamic tests that provide a central stimulus remain preferable in the assessment of patients with suspected ACTH deficiency.

The combined pituitary function test in children: an evaluation of the clinical usefulness of TRH and LHRH stimulation tests through a retrospective analysis of one hundred and twenty six cases

OBJECTIVE

The combined pituitary function test is routinely used in the endocrine investigation of short children. The TRH and luteinising hormone-releasing hormone (LHRH) response tests have been shown to be of minimal value in adults. We have evaluated the clinical utility of these tests in the context of combined pituitary function testing in children.

DESIGN

A retrospective analysis of basal hormone measurements and pituitary stimulation tests in relation to clinical assessment of pituitary function.

PATIENTS

One hundred and twenty-six children, 82 boys and 44 girls, aged 2-17 years, who had undergone pituitary function testing were studied.

RESULTS

The TSH response to TRH stimulation correlated directly with basal plasma TSH but not basal plasma total T4. In patients with an impaired response to stimulation, basal TSH concentrations were <2.0 mIU/l and significantly lower than in patients with a normal response (P < 0.0001). An impaired response to TRH stimulation had a positive predictive value of 0.43 and a negative predictive value of 0.90 for the diagnosis of hypopituitarism. A basal TSH concentration of <2.0 mIU/l had a positive predictive value of 0.22 and a negative predictive value of 0.92. A low basal T4 (normal range 60-140 nmol/l) in combination with an inappropriately low or normal basal TSH was always associated with a diagnosis of hypopituitarism. The responses of plasma LH and FSH to LHRH stimulation correlated directly with basal plasma LH and FSH concentrations. Basal gonadotrophin concentrations, basal sex hormone concentrations or response to LHRH stimulation could not distinguish patients with constitutional delay of growth and puberty from those with hypopituitarism. There was no apparent relationship between either basal gonadotrophin concentrations or response to LHRH stimulation and clinical assessment of pituitary function. In patients ≥13 years with constitutional delay of growth and puberty the median and interquartile ranges of basal LH and FSH were 1.4 IU/l (0.7-3.6) and 2.6 IU/l (2.2-5.2) respectively. The three hypopituitary patients in this study with chronological age ≥13 years had undetectable concentrations of both gonadotrophins. The response of LH and FSH to LHRH stimulation was significantly lower in patients ≥13 years with clinical hypopituitarism than in those with intact pituitary function (P <0.02).

CONCLUSION

TRH and LHRH tests in children with short stature appear to have little value over and above the baseline hormone measurements. An abnormal response to hormone stimulation is not diagnostic of hypothalamic-pituitary disease. We have demonstrated that neither TRH nor LHRH stimulation tests should be routinely used in the investigation of children with short stature.

Low-dose (1 microgram) adrenocorticotrophin (ACTH) stimulation as a screening test for impaired hypothalamo-pituitary-adrenal axis function: sensitivity, specificity and accuracy in comparison with the high-dose (250 microgram) test

OBJECTIVE

We have shown previously that in contrast to the standard high-dose 250-microgram ACTH test, a low-dose 1-microgram ACTH stimulation test correctly identified all patients with pituitary disease who had impaired hypothalamo-pituitary-adrenal (HPA) function. In this study we further compared the performances of these two tests as screening procedures for possible HPA impairment.

DESIGN

A comparison of the 1-microgram and the 250-microgram ACTH stimulation tests in healthy controls and in patients with pituitary disease whose HPA axis status was characterized formally by a gold standard test.

SUBJECTS

A total of 89 subjects were investigated: 27 healthy normal controls, 43 patients with pituitary disease and normal HPA function, and 19 patients with various pituitary diseases and impaired HPA function.

MEASURES

All 89 subjects underwent stimulation with 1 microgram ACTH; 80 also underwent the high-dose 250-microgram ACTH test. A receiver operating characteristic analysis (ROC) was performed to compare the tests.

RESULTS

Using a stimulated cortisol > 500 nmol/l as the criterion for a normal response, the 1-microgram ACTH stimulation identified 18 of the 19 subjects with impaired HPA function (94.7% sensitivity with a likelihood ratio of 0.0588 for a negative test). In contrast, 15/16 passed the high-dose test (a 6.2% sensitivity with a likelihood ratio of 0.875 for a negative test). All normal controls, and 36/43 patients with preserved HPA function, passed the 1-microgram ACTH test (90% specificity). This degree of accuracy was unrivalled by the high dose test at all the cut-off levels considered.

CONCLUSIONS

More sensitive and accurate, the low-dose 1-microgram ACTH test is as simple and safe as the standard 250-microgram test. We suggest it should replace it in screening for adrenal insufficiency.

Pituitary incidentalomas

The optimal strategy for hormonal screening of a patient with any incidentally discovered pituitary mass is unknown. The authors' review of the endocrinologic literature supports the view that such patients are at slightly increased risk for morbidity and mortality. This risk implies a benefit of early diagnosis for at least for some of the disorders, suggesting the importance of case finding. Nevertheless, the data in Table 1 illustrate that clinically diagnosed hormone-secreting pituitary tumors are far less common than incidentalomas. Clinically, one cannot accurately determine the approximately 0.5% of patients with incidentaloma who are at increased risk among the vast majority who are not. Given the limitations of diagnostic tests, effective hormonal screening requires a sufficiently high pretest probability to limit the number of false-positive results. This condition is met to varying degrees in the patient with a small incidentally discovered pituitary mass but no signs or symptoms of hormone excess. Even the more common lesions, such as prolactinoma, are relatively rare. [table: see text] Subjecting patients to unnecessary testing and treatment is associated with risk. In addition to its initial cost, testing may result in further expense and harm as false-positive results are pursued, producing the "cascade effect" described by Mold and Stein as a "chain of events (which) tends to proceed with increasing momentum, so that the further it progresses the more difficult it is to stop." The extensive evaluations performed for some patients with incidentally discovered masses may reflect the unwillingness of many physicians to accept uncertainty, even in the case of an extremely unlikely diagnosis. This unwillingness may be driven, in part, by fear of potential malpractice liability, the failure to appreciate the influence of prevalence data on the interpretation of diagnostic testing, or other factors. The major justification for further evaluation of these patients is not so much to avoid morbidity and mortality for the rare patient who truly is at increased risk but to reassure patients in whom further testing is negative and the physician. Physicians must take care not to create inappropriate anxiety in patients by overemphasizing the importance of an incidental finding unless it is associated with a realistic clinical risk. The authors' recommendations are based on currently available information to minimize the untoward effects of the cascade. As evidence accumulates, these recommendations may need to be revised. The benefit of the diagnosis of an adrenal or pituitary disorder must be considered in the context of the patient's overall condition. Additional studies are needed to analyze the clinical utility of hormonal screening for these common radiologic findings. Data from these studies can be used to identify critical gaps in knowledge and to adopt the epidemiologic methods of evaluation of evidence that have been applied to preventive measures. One must be careful to recognize lead-time bias, in which survival can appear to be lengthened when screening simply advances the time of diagnosis, lengthening the period of time between diagnosis and death without any true prolongation of life; and length bias, which refers to the tendency of screening to detect a disproportionate number of cases of slowly progressive disease and to miss aggressive cases that, by virtue of rapid progression, are present in the population only briefly. Physicians must avoid the pitfalls of overestimation of disease prevalence and of the benefits of therapy resulting from advances in diagnostic imaging. Clinical judgment based on the best available evidence should be complemented and not replaced by laboratory data.

Peripubertal prolactinomas: clinical presentation and long-term outcome with different therapeutic approaches

The evolution of prolactinomas in children and adolescents continues to be controversial. We report on the long-term evolution (2-20 yr) of prolactinomas in 40 patients (29 F, 11 M). In females, the age for the onset of symptoms ranged between 8 and 16 yr and the age at which diagnosis was made ranged from 15 to 19 yr; in males, ages ranged from 8 to 17 yr and from 13.8 to 19 yr, respectively. In females, there was predominance of microprolactinomas (22/ 29) and the symptomatology resulted from functional disorders, whereas in males there was predominance of macroprolactinomas (8/11) and symptoms were caused by tumor mass disorders. Surgery was used as primary therapy in nine patients and as supplemental therapy in six patients. Twenty-four patients were treated primarily with bromocriptine and seven with cabergoline. Of the nine patients treated primarily with surgery, only one achieved gonadotropic axis restoration; in 25/31 patients receiving drug therapy gonadotropic function was restored to normal. Fifteen patients showed complete resolution or substantial shrinkage of tumor.

CONCLUSION

In pediatric and adolescent age, there seem to be age- and sex-dependent differences in the clinical presentation of prolactinomas that cannot be accounted for only in terms of time of evolution. Drug therapy can control the disease, normalize prolactin levels and achieve gonadotropic axis restoration in most patients.

The midnight to morning urinary cortisol increment is an accurate, noninvasive method for assessment of the hypothalamic-pituitary-adrenal axis

The optimal method for assessing the hypothalamic-pituitary-adrenal axis (HPA) remains controversial. The insulin tolerance test (ITT) is considered the gold standard, but is invasive and potentially dangerous. The short Synacthen test (SST) is the most commonly used alternative, but its concordance with the ITT is poor. Using sleep as a reliable stimulus to ACTH release, we proposed that the increment in urinary cortisol levels between midnight and waking could provide a noninvasive, physiological means for the assessment of the HPA axis. Double voided urine samples were collected at home at midnight and waking in 40 patients with pituitary disease and 40 controls. Cortisol and creatinine levels were measured, and the cortisol/creatinine (Cort/Cr) ratio was calculated. The Cort/Cr increment was defined as the morning Cort/Cr ratio minus the midnight Cort/Cr ratio. The Cort/Cr increment of the patients was compared to the results of their ITT or SST. Using the results from the 40 controls, a normal Cort/Cr increment was defined as greater then 9. The positive predictive value of a Cort/Cr increment for the diagnosis of HPA insufficiency was 95%. These findings suggest that the midnight to morning Cort/Cr increment is a reliable, noninvasive alternative to the ITT/SST for assessment of the HPA.

The use of the short tetracosactrin test for the investigation of suspected pituitary hypofunction

The short Synacthen (tetracosactrin) test (SST) is an established method of assessing adrenocortical reserve, and is increasingly replacing the insulin tolerance test (ITT) for the assessment of the hypothalamic-pituitary-adrenal (HPA) axis. However, there is no consensus on how the test is performed, and various time points and routes of administration are used. The present study was done, first, to determine whether there was any difference in cortisol responses when Synacthen was administered intramuscularly compared with intravenously and, secondly, to compare cortisol responses at 30 and 60 min. We found no significant difference between the two routes of administration. However, cortisol responses at 60 min were significantly higher than at 30 min (P < 0.05). Previous validations for the use of the SST in place of the ITT have used cortisol responses 30 min after Synacthen. We conclude that where the SST is used to assess the HPA axis, cortisol response at 30 min after intravenous Synacthen should be used.