Nocturnal hypoglycaemia in ACTH and GH deficient children: role of continuous glucose monitoring

Hypoglycaemia in adrenal insufficiency

Adrenal insufficiency encompasses a group of congenital and acquired disorders that lead to inadequate steroid production by the adrenal glands, mainly glucocorticoids, mineralocorticoids and androgens. These may be associated with other hormone deficiencies. Adrenal insufficiency may be primary, affecting the adrenal gland's ability to produce cortisol directly; secondary, affecting the pituitary gland's ability to produce adrenocorticotrophic hormone (ACTH); or tertiary, affecting corticotrophin-releasing hormone (CRH) production at the level of the hypothalamus. Congenital causes of adrenal insufficiency include the subtypes of Congenital Adrenal Hyperplasia, Adrenal Hypoplasia, genetic causes of Isolated ACTH deficiency or Combined Pituitary Hormone Deficiencies, usually caused by mutations in essential transcription factors. The most commonly inherited primary cause of adrenal insufficiency is Congenital Adrenal Hyperplasia due to 21-hydroxylase deficiency; with the classical form affecting 1 in 10,000 to 15,000 cases per year. Acquired causes of adrenal insufficiency can be subtyped into autoimmune (Addison's Disease), traumatic (including haemorrhage or infarction), infective (e.g. Tuberculosis), infiltrative (e.g. neuroblastoma) and iatrogenic. Iatrogenic acquired causes include the use of prolonged exogenous steroids and post-surgical causes, such as the excision of a hypothalamic-pituitary tumour or adrenalectomy. Clinical features of adrenal insufficiency vary with age and with aetiology. They are often non-specific and may sometimes become apparent only in times of illness. Features range from those related to hypoglycaemia such as drowsiness, collapse, jitteriness, hypothermia and seizures. Features may also include signs of hypotension such as significant electrolyte imbalances and shock. Recognition of hypoglycaemia as a symptom of adrenal insufficiency is important to prevent treatable causes of sudden deaths. Cortisol has a key role in glucose homeostasis, particularly in the counter-regulatory mechanisms to prevent hypoglycaemia in times of biological stress. Affected neonates particularly appear susceptible to the compromise of these counter-regulatory mechanisms but it is recognised that affected older children and adults remain at risk of hypoglycaemia. In this review, we summarise the pathogenesis of hypoglycaemia in the context of adrenal insufficiency. We further explore the clinical features of hypoglycaemia based on different age groups and the burden of the disease, focusing on hypoglycaemic-related events in the various aetiologies of adrenal insufficiency. Finally, we sum up strategies from published literature for improved recognition and early prevention of hypoglycaemia in adrenal insufficiency, such as the use of continuous glucose monitoring or modifying glucocorticoid replacement.

Glucose pattern in children with classical congenital adrenal hyperplasia: evidence from continuous glucose monitoring

BACKGROUND

While the risk for hypoglycemia during acute illness is well described in children with classical congenital adrenal hyperplasia (CAH), there is little evidence for the prevalence of asymptomatic hypoglycemia and the daily glucose patterns in CAH. Herein, we explored the daytime glucose profile of children with classical CAH.

METHODS

We conducted an observational study in 11 children (6 female; age 3.1 years [1.4, 5.1]; body mass index 17.3 kg/m2 [15.6, 17.9]) with a genetic diagnosis of classical CAH receiving hydrocortisone and fludrocortisone replacement therapy. Participants underwent 2 14-day continuous glucose monitoring (CGM) sessions and an inpatient 24 h series cortisol and adrenocorticotropic hormone (ACTH) measures. Data were analyzed for 3 daytime lags (7 Am-4 Pm, 4 Pm-10pm, 10 Pm-7 Am) corresponding to the hydrocortisone dosing period with cortisol and ACTH measured before the hydrocortisone dose.

RESULTS

Eleven participants completed at least 1 CGM session, and 7 out of 11 underwent both the CGM session and the cortisol/ACTH serial measures. In the whole cohort, the percentage of time of sensor glucose values <70 mg/dL was higher during the 10 Pm-7 Am and the 7 Am-4 Pm time slots than in the late afternoon period (17% [7, 54] and 15% [6.8, 24] vs 2% [1.1, 16.7] during the periods 7 Am-4 Pm and 4 Pm-10 Pm, respectively [P = .006 and P = .003]). Nighttime hypoglycemia was mostly spent below the 65 mg/dL (10.9% [4.1, 34]). The glycemic pattern paralleled the nadir of daily cortisol at 7 Am (10.3±4.4 μg/dL). A greater percentage of time in hypoglycemia was associated with lower cortisol concentration at 7 Am and 10 Pm (P < .001 and P = .005).

CONCLUSIONS

Continuous glucose monitoring demonstrated a disrupted daily glucose pattern in children with CAH, paralleled by a lower cortisol concentration.

CLINICALTRIALS.GOV REGISTRATION

NCT04322435.

Dynamic Methods for Childhood Hypoglycemia Phenotyping: A Narrative Review

Hypoglycemia results from an imbalance between glucose entering the blood compartment and glucose demand, caused by a defect in the mechanisms regulating postprandial glucose homeostasis. Hypoglycemia represents one of the most common metabolic emergencies in childhood, potentially leading to serious neurologic sequelae, including death. Therefore, appropriate investigation of its specific etiology is paramount to provide adequate diagnosis, specific therapy and prevent its recurrence. In the absence of critical samples for biochemical studies, etiological assessment of children with hypoglycemia may include dynamic methods, such as in vivo functional tests, and continuous glucose monitoring. By providing detailed information on actual glucose fluxes in vivo, proof-of-concept studies have illustrated the potential (clinical) application of dynamic stable isotope techniques to define biochemical and clinical phenotypes of inherited metabolic diseases associated with hypoglycemia. According to the textbooks, individuals with glycogen storage disease type I (GSD I) display the most severe hypoglycemia/fasting intolerance. In this review, three dynamic methods are discussed which may be considered during both diagnostic work-up and monitoring of children with hypoglycemia: 1) functional in vivo tests; 2) in vivo metabolic profiling by continuous glucose monitoring (CGM); 3) stable isotope techniques. Future applications and benefits of dynamic methods in children with hypoglycemia are also discussed.

The utility of continuous glucose monitoring systems in the management of children with persistent hypoglycaemia

OBJECTIVES

Glucose monitoring is vital in children with persistent hypoglycaemia to reduce the risk of adverse neuro-behavioural outcomes; especially in children with hyperinsulinism. The role of continuous glucose monitoring (CGM) systems in monitoring glucose levels in this cohort is limited. The objective of this study was to ascertain the effectiveness of CGM and to evaluate parents' experience of using CGM for monitoring glucose levels in children with hypoglycaemia.

METHODS

Retrospective analysis of sensor glucose (SG) values from Dexcom G4 CGM with paired finger-prick blood glucose (BG) values was performed to determine the accuracy of CGM. The parent experience of CGM was assessed using a questionnaire administered to families of children with congenital hyperinsulinism currently attending the clinic.

RESULTS

SG data from 40 children (median age 6 months) with persistent hypoglycaemia (60% Hyperinsulinism) were analysed. The mean difference between 5,650 paired BG and SG values was 0.28 mmol/L. The sensitivity and specificity of CGM to identify severe hypoglycaemia (BG < 3.0 mmol/L) were 54.3% (95% CI: 39.0%, 69.1%) and 97.4% (95% CI: 96.9%, 97.8%) respectively. Parents (n=11) reported less anxiety (n=9), better sleep at night (n=7) and preferred to use CGM for monitoring (n=9).

CONCLUSIONS

Although the high number of false-positive readings precludes the routine use of CGM in the evaluation of hypoglycaemia, it avoids unnecessary BG testing during normoglycaemia. It is an acceptable tool for parents for monitoring their children who are at risk of hypoglycaemia. Newer CGM systems with improved accuracy at lower glucose levels have the potential to further improve monitoring.

Reverse circadian glucocorticoid treatment in prepubertal children with congenital adrenal hyperplasia

OBJECTIVES

Children with salt-wasting congenital adrenal hyperplasia (CAH) have an impaired function of steroid synthesis pathways. They require therapy with glucocorticoid (GC) and mineralocorticoid hormones to avoid salt-wasting crisis and other complications. Most commonly, children receive hydrocortisone thrice daily with the highest dose in the morning, mimicking the regular physiology. However, reverse circadian treatment (RCT) had been suggested previously. In this study, we aimed to determine the efficacy of RCT in prepubertal children with CAH by comparing the salivary 17-hydroxyprogesterone (s17-OHP) levels individually.

METHODS

In this retrospective study, we analyzed the records of children with classical CAH and RCT who were monitored by s17-OHP levels. The study included 23 patients. We identified nine prepubertal children with RCT schemes (three boys and six girls) and compared the s17-OHP levels in the morning, afternoon, and evening. The objective of this study was to demonstrate the non-effectiveness of RCT in terms of lowering the morning s17-OHP concentration. In addition, we compared s17-OHP day profiles in six patients on RCT and non-RCT therapy (intraindividually).

RESULTS

Eight of nine children with RCT showed higher s17-OHP levels in the morning compared to the evening. In addition, none of the children showed a significant deviation of development. Three children were overweight. No adrenal crisis or pubertal development occurred. Comparison of RCT and non-RCT regimens showed no difference in 17-OHP profiles.

CONCLUSIONS

Our data do not support the use of RCT schemes for GC replacement in children with CAH due to lack of benefits and unknown long-term risks.

Continuous Glucose Monitoring System in Acromegalic Patients: Possible Role in the Assessment of Glycemia Control

BACKGROUND

Acromegaly is characterized by an insulin resistance condition. There is a significant difference between the different types of therapy in relation to the glycometabolic framework. The blinded continuous glucose monitoring system (CGMS), throughout a period of maximum 6 days for a total of 288 glycemic registrations per day, identifies glycemic excursions and could constitute a valid device to understand the 24-hour glycemic profiles.

AIM OF THE STUDY

To compare the oral glucose tolerance test (OGTT) and CGMS methods in acromegalic patients to evaluate their glycemic profiles, in relation to different treatments for acromegaly.

METHODS

Thirty-five acromegalic patients were divided into 18 somatostatin analogs (SSA), 9 pegvisomant, and 8 successfully surgically treated. A 72-hour CGM was performed and, immediately after, an OGTT.

RESULTS

Results obtained from OGTT: 11/35 impaired fasting glucose, 6/35 impaired glucose tolerance, and 4/35 diabetes mellitus. A positive significant correlation was demonstrated between the OGTT peak and CGM peak in all of the patients, CGM peak of patients treated with SSA and those surgically treated, OGTT average and CGM area under concentration-time curve (AUC) for hyperglycemia of patients treated with SSA and those surgically treated, and CGM AUC for hyperglycemia of patients treated with SSA and those surgically treated.

CONCLUSIONS

Our results show a significantly higher response in terms of mean and peak OGTT in patients treated with SSA, both compared to the CGM study, and compared to the group of patients receiving pegvisomant. The CGM system could represent an instrument for the evaluation of the glycemic trend of acromegalic patients.

Current and future treatment options for adrenal insufficiency

PURPOSE OF REVIEW

Patients with adrenal insufficiency (AI) irrespective of being on glucocorticoid replacement therapy still suffer from increased morbidity and mortality. A major contributing factor is an inability of conventional glucocorticoid treatment to mirror the physiological cortisol rhythm. Novel strategies to replicate the cortisol rhythm using hydrocortisone infusion pumps and oral modified release hydrocortisone have now been developed and confirmed to offer benefits to patients.

RECENT FINDINGS

In the DREAM study, when compared to multiple daily dosing of glucocorticoids Plenadren reduced weight, was less immunosuppressive and resulted in a better quality of life besides reducing infections. Chronocort that provides the early morning rise in cortisol improves androgen concentrations compared to conventional glucocorticoid treatments in congenital adrenal hyperplasia (CAH). Physiological hydrocortisone infusion pumps improve cortisol profiles with better adrenocorticotrophic hormone, glucose control, and quality of life (QOL) with androgen levels better controlled in CAH.

SUMMARY

Advances in glucocorticoid replacement for patients with AI are ongoing. Novel approaches to managing AI, enabled by this armamentarium of drug formulations, aims to improve patient health. Currently, their use should be reserved for patients with metabolic complications, very poor QOL and difficult-to-treat CAH. Larger studies based on outcomes are essential to understand to what extent these strategies can replace conventional treatments.

Continuous glucose monitoring for hypoglycaemia in children: Perspectives in 2020

Hypoglycaemia in children is a major risk factor for adverse neurodevelopment with rates as high as 50% in hyperinsulinaemic hypoglycaemia (HH). A key part of management relies upon timely identification and treatment of hypoglycaemia. The current standard of care for glucose monitoring is by infrequent fingerprick plasma glucose testing but this carries a high risk of missed hypoglycaemia identification. High-frequency Continuous Glucose Monitoring (CGM) offers an attractive alternative for glucose trend monitoring and glycaemic phenotyping but its utility remains largely unestablished in disorders of hypoglycaemia. Attempts to determine accuracy through correlation with plasma glucose measurements using conventional methods such as Mean Absolute Relative Difference (MARD) overestimate accuracy at hypoglycaemia. The inaccuracy of CGM in true hypoglycaemia is amplified by calibration algorithms that prioritize hyperglycaemia over hypoglycaemia with minimal objective evidence of efficacy in HH. Conversely, alternative algorithm design has significant potential for predicting hypoglycaemia to prevent neuroglycopaenia and consequent brain dysfunction in childhood disorders. Delays in the detection of hypoglycaemia, alarm fatigue, device calibration and current high cost are all barriers to the wider adoption of CGM in disorders of hypoglycaemia. However, machine learning, artificial intelligence and other computer-generated algorithms now offer significant potential for further improvement in CGM device technology and widespread application in childhood hypoglycaemia.

A Single Episode of Hypoglycemia as a Possible Early Warning Sign of Adrenal Insufficiency

A 65-year-old woman without a history of diabetes mellitus was admitted for elective total knee arthroplasty for osteoarthrosis. There were no specific complaints except for knee flexion contractures, and the results of preoperative tests were unremarkable. On the day of surgery, the patient suffered from a hypoglycemic attack (52 mg/dL) after preoperative overnight fasting. A dextrose infusion immediately corrected the hypoglycemia, and a total knee arthroplasty was then performed. Although a hypoglycemic attack did not recur, further evaluation was required because of nausea that persisted after surgery. The morning serum cortisol level was 0.15 µg/dL with undetectable adrenocorticotropic hormone (ACTH), and the insulin-like growth factor-1 level was 9 ng/mL. An empty sella and bilateral adrenal atrophy were evident in imaging studies. ACTH and growth hormone (GH) did not respond to testing with corticotropin-releasing hormone and GH-releasing peptide-2, respectively. While serum cortisol did not increase on a rapid ACTH stimulation test, urinary free cortisol excretion responded to a prolonged ACTH stimulation test. Finally, the patient was diagnosed as having empty sella syndrome with ACTH and GH deficiencies. After the administration of hydrocortisone as maintenance replacement therapy, the patient's prolonged postoperative nausea disappeared. Adrenal insufficiency is latent in patients with hypoglycemia episodes. Because patients with adrenal insufficiency require appropriate perioperative corticosteroid supplementation, clinicians should give priority to identifying the underlying etiology of hypoglycemia over non-urgent elective surgery when these co-occur.

Novel insights into glucocorticoid replacement therapy for pediatric and adult adrenal insufficiency

Adrenal insufficiency is defined as impaired adrenocortical hormone synthesis. According to its source, the deficit is classified as primary (adrenal steroidogenesis impairment), secondary (pituitary adrenocorticotropic hormone deficit) or tertiary (hypothalamic corticotropin-releasing hormone deficit). The management of adrenal insufficiency resides primarily in physiological replacement of glucocorticoid secretion. Standard glucocorticoid therapy is shrouded in several controversies. Along the difficulties arising from the inability to accurately replicate the pulsatile circadian cortisol rhythm, come the uncertainties of dose adjustment and treatment monitoring (absence of reliable biomarkers). Furthermore, side effects of inadequate replacement significantly hinder the quality of life of patients. Therefore, transition to circadian hydrocortisone therapy gains prominence. Recent therapeutic advancements consist of oral hydrocortisone modified-release compounds (immediate, delayed and sustained absorption formulations) or continuous subcutaneous hydrocortisone infusion. In addition to illustrating the current knowledge on conventional glucocorticoid regimens, this review outlines the latest research outcomes. We also describe the management of pediatric patients and suggest a novel strategy for glucocorticoid replacement therapy in adults.

Human studies on hypothalamo-pituitary-adrenal (HPA) axis

The daily rhythm of the hypothalamo-pituitary-adrenal (HPA) axis is regulated by the central clock in the suprachiasmatic nucleus. Cortisol, a glucocorticoid, acts as a secondary messenger between the central clock and the peripheral tissues. Changes in clock time, as seen in shift workers, alters the HPA axis and results in metabolic disturbances associated with ill health. Depression, anorexia nervosa and obstructive sleep apnoea, are associated with cortisol rhythm phase shifts and increased cortisol exposure. Higher nocturnal cortisol exposure is observed in patients with Cushing's syndrome and adrenal incidentalomas with autonomous cortisol secretion and is associated with insulin resistance, and increased cardiovascular risk and mortality. A decrease in cortisol rhythm amplitude is seen in adrenal insufficiency, and despite replacement, patients have an impaired quality of life and increased mortality. Research on cortisol replacement has focused on replacing the cortisol daily rhythm by subcutaneous hydrocortisone infusions and oral modified release hydrocortisone formulations with the aim of improving disease control and quality of life.

Neonatal Hypoglycemia

Lower blood glucose values are common in the healthy neonate immediately after birth as compared to older infants, children, and adults. These transiently lower glucose values improve and reach normal ranges within hours after birth. Such transitional hypoglycemia is common in the healthy newborn. A minority of neonates experience a more prolonged and severe hypoglycemia, usually associated with specific risk factors and possibly a congenital hypoglycemia syndrome. Despite the lack of a specific blood glucose value that defines hypoglycemia, concern for substantial neurologic morbidity in the neonatal population has led to the generation of guidelines by both the American Academy of Pediatrics (AAP) and the Pediatric Endocrine Society (PES). Similarities between the 2 guidelines include recognition that the transitional form of neonatal hypoglycemia likely resolves within 48 hours after birth and that hypoglycemia that persists beyond that duration may be pathologic. One major difference between the 2 sets of guidelines is the goal blood glucose value in the neonate. This article reviews transitional and pathologic hypoglycemia in the neonate and presents a framework for understanding the nuances of the AAP and PES guidelines for neonatal hypoglycemia.

Neurological Complications of Endocrine Disease

The endocrine system is a complex group of organs and glands that relates to multiple other organs and systems in the body with the ultimate goal of maintaining homeostasis. This complex network functions through hormones excreted by several glands and released in the blood, targeting different body tissues and modulating their function. Any primary disorders affecting the endocrine glands and altering the amount of hormones synthesized and released will lead to disruption in the functions of multiple organs. The central nervous system of a developing child is particularly sensitive to endocrine disorders. A variety of neurological manifestations have been described as features of several endocrine diseases in childhood. Their knowledge may contribute to an early diagnosis of a particular endocrine condition, especially when more typical features are not present yet. In this article, we discuss specific neurological manifestations found in various endocrine disorders in children.

Ramadan fasting in patients with adrenal insufficiency

AIM

The risks of fasting during Ramadan in patients with adrenal insufficiency are unknown. The aims of this study were to evaluate these risks in such patients, to determine the risk factors and finally to set some recommendations.

METHODS

It is a cross-sectional study about 180 patients with known and treated adrenal insufficiency. The patients responded to a 14-item questionnaire concerning their knowledge about the disease and fasting during the last month of Ramadan.

RESULTS

There were 132 women and 48 men. The mean age was 47.6 ± 15.0 years (14-79). One hundred and thirty eight patients (76.7 %) were advised by their physician not to fast. Ninety-one patients (50.5 %) tried to fast. Complications occurred in 61 cases (67.0 %): asthenia in 88.5 % of cases, intense thirst in 32.8 %, symptoms of dehydration in 49.2 % and symptoms of hypoglycaemia in 18 %. One patient was hospitalized. Fifty-five patients (60.4 %) were able to fast for the whole month. Age, gender, duration of the disease, its primary origin, associated hypothyroidism, diabetes mellitus, hypertension or diabetes insipidus and daily dose of hydrocortisone did not significantly differ between fasters and non-fasters, full-month-fasters and partial-month-fasters, and fasters with complications and fasters without complications. The frequency of adequate knowledge about the disease was significantly higher in full-month-fasters vs. partial-month-fasters, and in fasters without complications vs. those with complications.

CONCLUSION

In patients with adrenal insufficiency, fasting can cause complications especially if the level of knowledge about the disease is low.