PseudoCushing: why a clinical challenge?

Cortisol: Analytical and clinical determinants

Cortisol, the main human glucocorticoid, is synthesized from cholesterol in the adrenal cortex and predominantly metabolized by the liver. Interpretation of quantitative results from the analysis of serum, urine and saliva is complicated by variation in circadian rhythm, response to stress as well as the presence of protein-bound and free forms. Interestingly, cortisol is the only hormone routinely measured in serum, urine, and saliva. Preanalytical and analytical challenges arise in each matrix and are further compounded by the use of various stimulation and suppression tests commonly employed in clinical practice. Although not yet included in clinical guidelines, measurement of cortisol in hair may be of interest in specific situations. Immunoassays are the most widely used methods in clinical laboratories to measure cortisol, but they are susceptible to interference from synthetic and endogenous steroids, generally producing a variable overestimation of true cortisol results, especially in urine. Analysis by mass spectrometry provides higher specificity and allows simultaneous measurement of multiple steroids including synthetic steroids, thus reducing diagnostic uncertainty. An integrated review of cortisol in various disease states is also addressed.

Evaluation of the hypothalamic-pituitary-adrenal axis in a case series of familial partial lipodystrophy

BACKGROUND

Familial partial lipodystrophy (FPL) is a rare genetic disease characterized by body fat abnormalities that lead to insulin resistance (IR). Clinical conditions linked to milder IR, such as type 2 diabetes (T2D) and metabolic syndrome, are associated with abnormalities of the hypothalamic-pituitary-adrenal (HPA) axis, but little is known about its activity in FPL.

METHODS

Patients meeting the clinical criteria for FPL were subjected to anthropometric, biochemical and hormone analyses. A genetic study to identify mutations in the genes encoding peroxisome proliferator-activated receptor gamma (PPARγ) was performed. Polycystic ovary syndrome and hepatic steatosis were investigated, and the patient body compositions were analyzed via dual X-ray energy absorptiometry (DXA). The HPA axis was assessed via basal [cortisol, adrenocorticotrophic hormone (ACTH), cortisol binding globulin, nocturnal salivary cortisol and urinary free cortisol (UFC)] as well as dynamic suppression tests (cortisol post 0.5 mg and post 1 mg dexamethasone).

RESULTS

Six patients (five female and one male) aged 17 to 42 years were included. In DXA analyses, the fat mass ratio between the trunk and lower limbs (FMR) was > 1.2 in all phenotypes. One patient had a confirmed mutation in the PPARγ gene: a novel heterozygous substitution of p. Arg 212 Trp (c.634C>T) at exon 5. HPA sensitivity to glucocorticoid feedback was preserved in all six patients, and a trend towards lower basal serum cortisol, serum ACTH and UFC values was observed.

CONCLUSIONS

Our findings suggest that FPL is not associated with overt abnormalities in the HPA axis, despite a trend towards low-normal basal cortisol and ACTH values and lower UFC levels. These findings suggest that the extreme insulin resistance occurring in FPL may lead to a decrease in HPA axis activity without changing its sensitivity to glucocorticoid feedback, in contrast to the abnormalities in HPA axis function in T2D and common metabolic syndrome.

Physiolgic hypercortisolism at onset of celiac disease in a girl: A case report

RATIONALE

Celiac disease (CD) is an autoimmune disorder induced by dietary gluten in genetically predisposed subjects. Activation of the hypothalamic-pituitary-axis (HPA) can occur in patients with CD; however, this condition has never been described in overweight/obese CD children.

PATIENT CONCERNS

A 12-year-old girl with CD was admitted with mild acanthosis nigricans of the armpits, groin and neck. Recently, extra fat appeared around the neck, and moon face was observed. The abdomen was globular and meteoric, treatable and not aching. She weighed 64 kilos (75°-97° percentile) and was 146 centimeters tall (3°-25° percentile) with a body mass index of 30 kg/mq. Laboratory tests revealed hypertriglyceridemia and positive anti-transglutaminase IgA. Cortisoluria was determined. Serum ACTH was normal.

DIAGNOSES

This paper reports a case of a girl with CD in which both obesity and activation of HPA activity were noted.

INTERVENTIONS

During follow-up, anti-transglutaminase IgA increased to 201.5 UI/mL. The patient was positive for anti-endomysium antibodies, and the HLA DQ2 haplotype was identified, confirming a diagnosis of CD.

OUTCOMES

Despite a gluten-free diet, obesity and hyperadrenalism persisted, and anti-transglutaminase antibodies remained elevated. In addition, high cortisoluria persisted. A high-dose suppression dexamethasone test (8 mg) produced negative results with a morning cortisol value of 1 ng/mL, suggesting the diagnosis of pseudo-Cushing's syndrome.

LESSONS

This case highlights that the first manifestation of CD could be being overweight, and this finding seems to support the need to prescribe laboratory tests for CD not only to children with failure to thrive, as commonly recommended, but also to those with increased body weight.