Addison's Disease Does Not Cause Thrombocytosis
No, Addison's disease does not cause high platelets (thrombocytosis). In fact, there is no established association between primary adrenal insufficiency and elevated platelet counts in the medical literature.
Hematologic Abnormalities in Addison's Disease
The typical laboratory findings in Addison's disease are related to electrolyte disturbances rather than platelet abnormalities 1:
- Hyponatremia is present in approximately 90% of newly presenting cases, caused by sodium loss in urine and impaired free water clearance 1
- Hyperkalaemia occurs in approximately 50% of patients at diagnosis due to aldosterone deficiency 1
- Anemia may be present but is not a defining feature 2, 3
Platelet counts are not characteristically affected in Addison's disease. The consensus guidelines on primary adrenal insufficiency do not list thrombocytosis or any platelet abnormalities as clinical manifestations of the condition 1.
When to Consider Alternative Diagnoses
If a patient with Addison's disease presents with thrombocytosis, you should investigate other causes 4:
Secondary (Reactive) Thrombocytosis
- Chronic inflammatory conditions including autoimmune diseases that may coexist with Addison's disease 4
- Iron deficiency anemia, which accounts for 11% of secondary thrombocytosis cases 4
- Infection or inflammation, particularly if the patient is experiencing an adrenal crisis 4
- Malignancy, including solid tumors or lymphoproliferative disorders 4
Primary Thrombocytosis
- Myeloproliferative neoplasms such as essential thrombocythemia, polycythemia vera, or primary myelofibrosis, diagnosed by JAK2V617F, CALR, or MPL mutations 4
Important Clinical Caveat
Always exclude pseudothrombocytopenia before pursuing extensive workup. Examination of the peripheral blood smear is mandatory to confirm true thrombocytosis and exclude laboratory artifact 5, 4. This is particularly important because false platelet counts can occur due to technical issues with blood collection 5.
Coexisting Autoimmune Conditions
Approximately 50% of patients with Addison's disease have other autoimmune conditions 1:
- Autoimmune thyroid disease
- Type 1 diabetes mellitus
- Autoimmune gastritis with vitamin B12 deficiency
- Celiac disease 1
If thrombocytosis is present, consider whether a separate inflammatory or autoimmune process is driving the elevated platelet count rather than attributing it to Addison's disease itself 1, 4.