Case-Based Learning: Adrenal Insufficiency With Initially Preserved Electrolytes

Abstract

Adrenal insufficiency is a potentially life-threatening endocrine disorder commonly characterized by hypotension, fatigue, and electrolyte disturbances such as hyponatremia and hyperkalemia. However, early presentations may feature preserved electrolytes, making diagnosis challenging. This review explores adrenal insufficiency in the context of initially normal serum electrolytes, emphasizing the importance of clinical suspicion, understanding underlying mechanisms, and timely intervention. Recent evidence, guideline recommendations, and case-based perspectives are discussed to inform clinical practice and highlight diagnostic nuances.

Introduction

Adrenal insufficiency (AI) results from inadequate production of glucocorticoids and, in some cases, mineralocorticoids by the adrenal cortex. While classic features include electrolyte abnormalities, some patients, particularly in the early stages or with partial adrenal insufficiency, may present with non-specific symptoms and preserved electrolytes. Recognizing AI in such scenarios is critical to prevent diagnostic delays and adverse outcomes. This article provides a comprehensive, evidence-based review tailored to clinicians, focusing on the diagnostic and therapeutic complexities of AI with initially normal laboratory findings.

Epidemiology / Disease Burden

Primary adrenal insufficiency, or Addison’s disease, has an estimated prevalence of 100-140 cases per million in Western populations, with secondary AI being more common due to pituitary or hypothalamic dysfunction. Incidence rates vary globally, influenced by autoimmune prevalence, infectious etiologies, and iatrogenic factors. Despite being rare, AI disproportionately contributes to morbidity and mortality due to diagnostic challenges, particularly in resource-limited settings. Under-recognition in patients with subtle presentations, including preserved electrolytes, perpetuates underdiagnosis and delayed treatment.

Pathophysiology

AI arises from destruction or dysfunction of the adrenal cortex (primary AI) or impaired ACTH secretion (secondary/tertiary AI). Cortisol deficiency impairs vascular tone, glucose homeostasis, and stress adaptation. In primary AI, aldosterone deficiency typically leads to sodium loss and potassium retention. However, in the early phase of disease or with partial gland involvement, residual aldosterone secretion may initially preserve electrolyte balance. Secondary AI usually spares mineralocorticoid synthesis, further explaining normal electrolyte findings in some cases. Understanding these mechanisms is crucial for interpreting laboratory results in clinical context.

Risk Factors

Risk factors for AI include autoimmune diseases (notably polyglandular autoimmune syndromes), chronic glucocorticoid use with abrupt withdrawal, pituitary or hypothalamic disorders, infiltrative diseases (e.g., tuberculosis, metastases), adrenal hemorrhage (e.g., Waterhouse-Friderichsen syndrome), and genetic conditions such as congenital adrenal hyperplasia. In clinical practice, at-risk patients may present with subtle or atypical symptoms, particularly when electrolyte homeostasis is maintained early in the disease course.

Clinical Features

Classic symptoms of AI include fatigue, anorexia, weight loss, gastrointestinal disturbances, hypotension, and hyperpigmentation (in primary AI). Electrolyte abnormalities, particularly hyponatremia and hyperkalemia, are often considered hallmark features. However, in cases with preserved electrolytes, clinicians must rely on non-specific symptoms and a high index of suspicion. Early or partial AI may present with isolated fatigue, orthostatic hypotension, or mild gastrointestinal symptoms. Stressors such as infection or surgery can precipitate adrenal crises even when baseline electrolytes are normal, emphasizing the need for vigilance.

Diagnosis

Diagnosis of AI with preserved electrolytes requires a systematic approach. Baseline serum cortisol, particularly morning levels, provides initial screening. ACTH stimulation testing remains the gold standard for confirmation. Plasma ACTH concentrations help differentiate primary from secondary AI. In cases with initially normal electrolytes, repeated testing and dynamic assessment may be necessary, particularly in patients with compatible clinical features. Additional investigations include renin, aldosterone, and autoantibody panels, as well as pituitary imaging if secondary AI is suspected. Case-based learning reinforces the importance of clinical acumen in recognizing AI despite equivocal laboratory findings.

Treatment & Management

Management involves prompt glucocorticoid replacement, typically with hydrocortisone, and mineralocorticoid supplementation (fludrocortisone) in primary AI. In cases with preserved electrolytes, glucocorticoid therapy remains the cornerstone, with close monitoring of fluid and electrolyte status. Patient education on stress dosing and sick day rules is essential. Acute adrenal crisis warrants intravenous hydrocortisone and isotonic saline. Early recognition and treatment initiation, even in the absence of classic laboratory derangements, are paramount to preventing complications.

Recent Advances / Emerging Therapies

Contemporary research has focused on refining diagnostic tools, including salivary cortisol assays and novel biomarkers for early AI detection. Modified-release hydrocortisone aims to better mimic physiological circadian rhythms, potentially improving quality of life and reducing metabolic complications. Ongoing trials are evaluating alternative steroid formulations and individualized dosing protocols. Advances in genetic screening facilitate early diagnosis in familial or syndromic cases. Telemedicine platforms are increasingly used for patient education and management, especially for those at risk for adrenal crises.

Guideline Recommendations

Major guidelines, including those from the Endocrine Society, recommend high clinical suspicion for AI in patients with compatible symptoms, even if electrolytes are normal. Early dynamic testing and prompt initiation of glucocorticoid replacement are advised to mitigate risks. Guidelines emphasize patient education, crisis prevention, and regular follow-up. Endocrinology referral is recommended in diagnostic uncertainty or refractory cases. Multidisciplinary care is crucial for optimal outcomes.

Conclusion

Adrenal insufficiency with initially preserved electrolytes poses a significant diagnostic challenge due to non-specific symptoms and the absence of classic laboratory abnormalities. Awareness of this atypical presentation, combined with a thorough understanding of pathophysiology and risk factors, is essential for timely diagnosis and management. Recent advances in diagnostics and therapeutics, along with adherence to evidence-based guidelines, support improved patient outcomes. Clinicians must maintain a high index of suspicion and consider AI in differential diagnosis, even when electrolyte disturbances are not apparent.