Conn syndrome from an aldosterone-secreting adrenal gland adenoma is the most common form of primary aldosteronism and subsequent hypertension. Untreated Conn syndrome is associated with sight-threatening ocular and life-threatening cardiovascular complications.
A 44-year-old man presented with a 1-day history of headache and vision loss in the right eye. The headache was described as frontal, parietal, and periorbital in location. The visual change was sudden in onset and described as “looking through film.”
The patient had been diagnosed with hypertension and started on telmisartan 5 weeks before. Past medical history was also significant for hypercholesterolemia, obstructive sleep apnea, and a 15-pack-year history of smoking. The patient was not on any other medications.
On examination, blood pressure was 216/146 mmHg and heart rate was 110 beats per minute. Other vital signs were within normal limits. Visual acuity was counting fingers in the right eye and 6/5 in the left eye. There was a right relative afferent pupillary defect. Anterior segment examination of both eyes was within normal limits. Examination of the right retina revealed signs consistent with a central retinal vein occlusion (CRVO): four quadrants of deep and superficial intraretinal hemorrhages with cotton wool spots; significant right optic disc swelling and macular edema associated with venous dilation and tortuosity. Posterior segment examination of the left eye demonstrated arteriovenous nipping.
The patient was admitted to hospital under the medical team. After he was switched to an alpha-blocker and long-acting calcium channel blocker for control of his hypertension, he was found to have normal electrolytes, an upright renin level of 3.0 mIU/L, an aldosterone level of 759 pmol/L, and aldosterone:renin ratio of 253. Computed tomography showed a well-circumscribed lesion measuring 11.1 × 11.1 × 9.1 mm in the medial limb of the left adrenal gland, consistent with an aldosterone-secreting adenoma (Figure 1). Saline infusion test confirmed the diagnosis of Conn syndrome. There was no contributory hypercoagulability or vasculitis found.
Although preferred treatment of his Conn syndrome would have been removal of the lesion, cannulation of the adrenal vein to demonstrate an aldosterone gradient was not possible. The patient is therefore being managed with spironolactone to good effect, with control of his hypertension.
His eye improved without any ocular treatment as his blood pressure normalized. Twelve months after the event, his visual acuity was 6/6.
Retinal venous occlusive disease is the second most common retinal vascular disease after diabetic retinopathy.1 This case highlights the importance of appropriate investigation for cases of CRVO, especially in the context of a young patient. Despite having no hypercoagulable or vasculitic risk factors, further investigation of hypertension yielded the diagnosis of Conn syndrome.
To the best of our knowledge, this is the first reported case of Conn syndrome presenting as CRVO in the context of malignant hypertension. Conn syndrome is a form of primary aldosteronism because of an aldosterone-producing adenoma. Conn syndrome constitutes 77.4% of primary aldosteronism,2 with other causes being because of adrenal carcinoma, primary adrenal hyperplasia, and familial hyperaldosteronism. The prevalence of primary aldosteronism in hypertensive patients is 15%.3
The classic presenting signs of Conn syndrome are hypertension and hypokalemia, although potassium levels may be normal, as in our patient. Use of aldosterone:renin ratio to screen patients with hypertension has allowed detection of nonhypokalemic patients with Conn syndrome. Conn syndrome should also be suspected in cases of refractory hypertension. However, although blood pressure may be severely elevated, the malignant level seen in our patient is uncommon.4
Central retinal vein occlusion in persons aged 43 years to 69 years is associated with a doubling of the risk of cardiovascular mortality.1 This is important because untreated Conn syndrome is itself associated with greater cardiovascular complications (stroke, myocardial infarction, or sustained arrhythmia) compared with other causes of hypertension.5 However, the increased cardiovascular risk subsides after appropriate treatment with surgical resection and/or a mineralocorticoid receptor antagonist. One in two patients with Conn syndrome benefits from adrenal surgery alone, although this is not always possible, as seen in our case.
Although >90% of CRVO occurs in patients older than 50 years, it is also seen in younger age groups.6,7 Central retinal vein occlusion in a younger population is usually attributed to a hypercoagulable or vasculitic etiology.8 Lahey et al9 found at least one abnormal laboratory value suggesting systemic hypercoagulability in 27% of CRVO patients younger than 56 years. Other studies have demonstrated an increased incidence of various coagulation abnormalities, such as protein C and S deficiency, activated protein C resistance, Factor V Leiden, antiphospholipid antibodies, hyperhomocysteinemia, antithrombin III deficiency, prothrombin gene mutations, and abnormal fibrinogen levels.10 Hyperviscosity from blood dyscrasias, dysproteinemias, and dehydration have also been reported with CRVO.10
Interestingly, 12 months after his ischemic CRVO, our patient had an uncommonly good visual outcome of 6/6 after normalization of his blood pressure. This may be because of recanalization of his central retinal vein with appropriate cardiovascular management. We also note that the fellow eye of our patient showed mild hypertensive retinopathy with arteriovenous nipping, but no evidence of CRVO. It has been reported that the fellow eye may develop retinal vein occlusion in approximately 7% of patients within 2 years,6 highlighting the importance of investigating and managing underlying risk factors in young patients with CRVO.
Patients presenting with malignant hypertension should undergo ophthalmic assessment if they have visual symptoms. We also recommend thorough assessment of all hypertensive patients presenting with CRVO, particularly those younger than 50 years, because Conn syndrome is a possible underlying cause.
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