Idiopathic erythrocytosis: A diagnostic and management challenge with emerging areas for exploration

Despite published algorithms for approaching the work-up of erythrocytosis, a significant proportion of patients are left with uncertainty as to its aetiology and prognosis. The term 'idiopathic erythrocytosis' (IE) is applied when known primary and secondary aetiologies have been ruled out. However, the assignment of secondary aetiologies is not always straightforward or evidence based, which can lead to misdiagnosis and heterogeneity in cohort studies. Furthermore, new studies have identified germline or somatic mutations that may affect prognosis. Epidemiological and cohort data are inconsistent as to whether IE increases the risk for complications such as arterial and venous thromboembolism, clonal transformation or comorbid conditions. Randomized trials assessing the role of phlebotomy for long-term management of IE have not been performed, so treatment remains a vexing problem for clinicians. Standardization of terminology and testing strategies, including comprehensive genetic screening in clinical research, are key to refining our understanding of IE.

A comparison between erythrocytapheresis and venesection for the treatment of JAK2-mutated polycythaemia

BACKGROUND

JAK2-mutated polycythaemia vera (PV) is associated with reduced survival because of thrombotic events and haematological disease transformation. Therapeutic venesection has traditionally been used to lower haematocrit, but the technique of erythrocytapheresis has emerged over the last decade.

AIM

To compare erythrocytapheresis with venesection as treatment for PV by assessing medical efficacy and financial viability.

METHODS

One hundred sixteen patients with PV who received red cell depletion therapy at Barwon Health between 2014 and 2021 were identified. The haematocrit drop after each session, interval between treatment times and number of sessions required to achieve a haematocrit <0.45 were compared with an independent t test. Thrombosis rates were compared with Pearson's chi-squared test. Cost-funding analysis was done by assessing the Weighted Inlier Equivalent Separation and National Weighted Activity Unit funding models.

RESULTS

Patients treated with erythrocytapheresis achieved a greater haematocrit drop each treatment session (0.075 vs 0.03, P < 0.01), required fewer sessions to achieve a haematocrit <0.45 (1 vs 4, P < 0.01) and experienced fewer thrombotic complications (8.7% vs 32.1%, P = 0.02) than those treated with venesection. Cost-funding analysis demonstrated that erythrocytapheresis was more financially viable with a surplus of AU$297 per session compared to a deficit of AU$176 with venesection. Even if funding for venesection is increased, the cost of erythrocytapheresis may be mitigated by a lower number of procedures required per year (3.8 vs 5.3, P < 0.01).

CONCLUSIONS

Erythrocytapheresis is more efficacious than venesection for the treatment of PV and is accompanied by rapid reductions in haematocrit and reduced thrombotic complications.

JAK2 Unmutated Polycythaemia-Real-World Data of 10 Years from a Tertiary Reference Hospital

(1) Background: Polycythaemia is defined by an increase in haemoglobin (Hb) concentration, haematocrit (Hct) or red blood cell (RBC) count above the reference range adjusted to age, sex and living altitude. JAK2 unmutated polycythaemia is frequent but under-investigated in original publications. In this retrospective cohort study, we investigated the clinical and laboratory data, underlying causes, management and outcomes of JAK2 unmutated polycythaemia patients. (2) Methods: The hospital database was searched to identify JAK2 unmutated patients fulfilling WHO 2016 Hb/Hct criteria for PV (Hb >16.5 g/dL in men and >16 g/dL in women, or Hct > 49% in men and >48% in women, or RBC mass > 25% above mean normal predicted value) between 2008 and 2019. Clinical and laboratory data were collected and analysed. (3) Results: From 727,731 screened patients, 294 (0.04%) were included, the median follow-up time was 47 months. Epo and P50 showed no clear pattern in differentiating causes of polycythaemia. In 30%, the cause remained idiopathic, despite extensive work-up. Sleep apnoea was the primary cause, also in patients under 30. Around 20% had received treatment at any time, half of whom had ongoing treatment at the end of follow-up. During follow-up, 17.2% developed a thromboembolic event, of which 8.5% were venous and 8.8% arterial. The mortality was around 3%. (4) Conclusions: Testing for Epo and P50 did not significantly facilitate identification of underlying causes. The frequency of sleep apnoea stresses the need to investigate this condition. Idiopathic forms are common. A diagnostic flowchart based on our data is proposed here. NGS testing should be considered in young patients with persisting polycythaemia, irrespective of Epo and P50 levels.

Pseudo-pheochromocytoma due to obstructive sleep apnea: a case report

SUMMARY

Obstructive sleep apnea (OSA) is a condition of intermittent nocturnal upper airway obstruction. OSA increases sympathetic drive which may result in clinical and biochemical features suggestive of pheochromocytoma. We present the case of a 65-year-old male with a 2.9-cm left adrenal incidentaloma on CT, hypertension, symptoms of headache, anxiety and diaphoresis, and persistently elevated 24-h urine norepinephrine (initially 818 nmol/day (89-470)) and normetanephrine (initially 11.2 µmol/day (0.6-2.7)). He was started on prazosin and underwent left adrenalectomy. Pathology revealed an adrenal corticoadenoma with no evidence of pheochromocytoma. Over the next 2 years, urine norepinephrine and normetanephrine remained significantly elevated with no MIBG avid disease. Years later, he was diagnosed with severe OSA and treated with continuous positive airway pressure. Urine testing done once OSA was well controlled revealed complete normalization of urine norepinephrine and normetanephrine with substantial symptom improvement. It was concluded that the patient never had a pheochromocytoma but rather an adrenal adenoma with biochemistry and symptoms suggestive of pheochromocytoma due to untreated severe OSA. Pseudo-pheochromocytoma is a rare presentation of OSA and should be considered on the differential of elevated urine catecholamines and metanephrines in the right clinical setting.

LEARNING POINTS

Obstructive sleep apnea (OSA) is a common condition among adults. OSA may rarely present as pseudo-pheochromocytoma with symptoms of pallor, palpitations, perspiration, headache, or anxiety. OSA should be considered on the differential of elevated urine catecholamines and metanephrines, especially in patients with negative metaiodobenzylguanidine (MIBG) scan results.

Prevalence of polycythaemia with different formulations of testosterone therapy in transmasculine individuals

BACKGROUND

Masculinising hormone therapy with testosterone is used to align an individual's physical characteristics with his or her gender identity. Testosterone therapy is typically administered via intramuscular or transdermal routes, and polycythaemia is the most common adverse event.

AIMS

To compare the risk of polycythaemia with different formulations of testosterone therapy in transmasculine individuals.

METHODS

A retrospective cross-sectional analysis was undertaken of transmasculine individuals at a primary and secondary care clinic in Melbourne, Australia. A total of 180 individuals who were on testosterone therapy for >6 months was included. Groups included those receiving: (i) intramuscular testosterone undecanoate (n = 125); (ii) intramuscular testosterone enantate (n = 31); or (iii) transdermal testosterone (n = 24). Outcome was prevalence of polycythaemia (defined as haematocrit > 0.5).

RESULTS

Mean age was 28.4 (8.8) years, with a median duration of testosterone therapy of 37.7 (24.2) months; 27% were smokers. There was no difference between groups in serum total testosterone concentration measured. While there was no difference between groups in haematocrit, there was a higher proportion of patients with polycythaemia in those who were on intramuscular testosterone enantate (23.3%) than on transdermal testosterone (0%), P = 0.040. There was no statistically significant difference in polycythaemia between intramuscular testosterone undecanoate (15%) and transdermal testosterone, P = 0.066 nor between intramuscular testosterone enantate and undecanoate, P = 0.275.

CONCLUSIONS

One in four individuals treated with intramuscular testosterone enantate and one in six treated with testosterone undecanoate had polycythaemia. No individual treated with transdermal testosterone had polycythaemia. This highlights the importance of regular monitoring of haematocrit in transmasculine individuals treated with testosterone, and findings may inform treatment choices.

Prevalence of and risk factors for high-altitude hyperuricaemia in Bai individuals: a cross-sectional study

OBJECTIVE

Hyperuricaemia is common in Bai individuals; however, its prevalence remains unclear. This work aimed to investigate high-altitude hyperuricaemia prevalence and risk factors in Bai individuals.

METHODS

All eligible participants of Bai ethnicity (aged ≥18 years and undergoing routine medical examination at the People's Hospital of Jianchuan County between January and December 2019) were consecutively enrolled. Demographic and laboratory data were collected to investigate hyperuricaemia prevalence and associated risk factors.

RESULTS

A total of 1393 participants were assessed, comprising 345 (24.8%) with hyperuricaemia showing a male predominance (287/865 [33.2%] males versus 58/528 [11.0%] females). Hyperuricaemia prevalence was significantly higher in participants aged ≥50 years (100/332 [30.1%]) versus those aged 30-40 years (59/308 [19.2%]), and in overweight/obese individuals compared with those showing an underweight or normal body mass index (BMI; 267/885 [30.2%] versus 78/508 [15.4%]). Finally, haemoglobin concentrations and serum uric acid levels were positively correlated.

CONCLUSION

Besides traditional risk factors, including age, sex and BMI, polycythaemia due to prolonged exposure to high altitude may also cause hyperuricaemia in Bai individuals residing in Yunnan Province.

Pitfalls of delaying the diagnosis of hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT; Osler–Weber–Rendu disease) is an autosomal dominant vascular disease characterized by nosebleeds, mucocutaneous telangiectases, visceral arteriovenous malformations (AVM) and a first-degree relative with HHT. Diagnosis is definite if three or four criteria are present. This case report describes a 19-year-old male with incidentally detected polycythaemia and an associated soft-tissue opacity over the left lower lobe on his frontal chest radiogram. He had experienced dyspnoea on exertion since infancy and clubbing at physical examination. Polycythaemia vera, chronic obstructive pulmonary disease, sleep apnoea and cyanotic congenital heart disease were excluded. Chest computed tomography (CT) was initially refused by the patient, but 3 years later he presented with severe epistaxis. Considering the unvarying soft tissue mass and erythrocytosis, an HHT-associated pulmonary AVM (PAVM) was eventually confirmed by chest CT. A pathogenic family-specific ENG c.817-2 A>C mutation was detected in the patient. The large PAVM was successfully treated using AMPLATZER™ vascular plug embolization. A combination of the multisystemic nature of his symptoms, the age-related penetrance of HHT symptoms and insufficient patient compliance delayed the diagnosis of HHT in this current case.

Management of late presentation congenital heart disease

In many parts of the world, mostly low- and middle-income countries, timely diagnosis and repair of congenital heart diseases (CHDs) is not feasible for a variety of reasons. In these regions, economic growth has enabled the development of cardiac units that manage patients with CHD presenting later than would be ideal, often after the window for early stabilisation - transposition of the great arteries, coarctation of the aorta - or for lower-risk surgery in infancy - left-to-right shunts or cyanotic conditions. As a result, patients may have suffered organ dysfunction, manifest signs of pulmonary vascular disease, or the sequelae of profound cyanosis and polycythaemia. Late presentation poses unique clinical and ethical challenges in decision making regarding operability or surgical candidacy, surgical strategy, and perioperative intensive care management.

Hb Baden: a rare high affinity haemoglobin variant and its management

Haemoglobin Baden is a rare variant haemoglobin which has only recently been clinically and functionally characterised. We present the case of a young adult male patient who presented with an erythrocytosis but was clinically asymptomatic. His mother was also diagnosed retrospectively having presented with erythrocytosis being treated with regular venesections. We discuss the management plan and potential significance of being a carrier of this rare haemoglobin variant.

Systemic capillary leak syndrome: recognition prevents morbidity and mortality

Idiopathic systemic capillary leak syndrome (SCLS) is extremely rare but carries a high morbidity and mortality. The diagnosis is made clinically by a classic triad of hypotension, hypoalbuminaemia and haemoconcentration. There have been recent advances in understanding the pathophysiological basis for SCLS and in effective prophylaxis. We report a case of SCLS to increase awareness of the condition and to highlight the benefits of prophylactic intravenous immunoglobulin in this condition.

Myeloproliferative neoplasms

The myeloproliferative neoplasms that are associated with the JAK2 mutation are a heterogeneous group of disorders. The additional mutations that result in the clinical phenotype are still the subject of research. As more than one mutation is involved, and as JAK2 has a necessary physiological role (unlike BCR-ABL), the development of targeted therapy remains a challenge. Although new drugs are being developed, treatment at present is predominantly with agents that have been in use for many years. An understanding of the need to control the thrombotic risk has, however, led to improved survival rates such that ET and PV can be seen as chronic diseases.

Polycythaemia treated with nephrectomy

Unilateral renal cystic disease (URCD) is a rare, non-familial non-progressive renal disorder not associated with cysts in other organs in contrast to autosomal dominant polycystic kidney disease. Only 55 cases have been published in the world literature. Renal diseases are a well-recognized etiology of secondary erythrocytosis but not in URCD. We can present at case of URCD and secondary polycythaemia. Only one case with similar history has been reported, but in our case, the polycythaemia was confirmed by measuring the erythropoietin (EPO) level in the cyst fluid.

Angiotensin-converting enzyme inhibitor fetopathy: long-term outcome

Fetal exposure to angiotensin-converting enzyme inhibitors (ACEIs) is associated with increased neonatal morbidity and mortality. Long-term follow-up of three patients with fetal ACEI exposure revealed impaired renal function in two, severe hypertension and proteinuria in one and isolated polycythaemia in all three. Careful long-term follow-up of children with ACEI fetopathy is recommended.

Systematic review of the optimal fluid for dilutional exchange transfusion in neonatal polycythaemia

OBJECTIVES

Several studies have shown the efficacy of dilutional exchange transfusion (DET) in reducing haematocrit (Ht) and relieving clinical symptoms in neonatal polycythaemia. We conducted a systematic review to determine the efficacy of crystalloid versus colloid solutions used in DET in an effort to identify the best solution to replace red blood cells.

METHODS

The Cochrane Library, MEDLINE, and EMBASE were searched for relevant randomised controlled trials. Quality assessment and data analysis were performed using the methods and software of the Cochrane Collaboration. Relative risk (RR) and weighted mean difference (WMD) were calculated as measures of effect for categorical and continuous outcome data, respectively. Ninety five percent confidence intervals (95% CI) were calculated and a fixed effect model was used for meta-analysis.

RESULTS

Six studies with a total of 235 newborns matched our inclusion criteria. When comparing crystalloid and colloid replacement solutions for DET, there was a clinically unimportant difference in Ht at 2-6 h and at 24 h in favour of colloidal solutions (WMD 2.29% (95% CI 1.28 to 3.31) and 1.74% (95% CI 0.80 to 2.68), respectively). This difference in post DET Ht was more evident when normal saline was compared to plasma but absent when normal saline was compared to 5% albumin.

CONCLUSION

There is little difference in effectiveness between plasma, 5% albumin, and crystalloid solutions. Since normal saline is cheap, readily available, and does not carry the potential risk of transfusion associated infection, normal saline is the optimal dilutional fluid for exchange transfusion in polycythaemic neonates.

Short and long term outcomes following partial exchange transfusion in the polycythaemic newborn: a systematic review

BACKGROUND

Severe polycythaemia in the neonate may produce symptoms due to hyperviscosity and may be associated with serious complications. Partial exchange transfusion will reduce the packed cell volume.

OBJECTIVE

To determine whether partial exchange transfusion in term infants with polycythaemia (symptomatic and asymptomatic) is associated with improved short and long term outcomes.

SEARCH STRATEGY

Medline, EMBASE, and the Cochrane Controlled Trials Register of the Cochrane Library were searched. The following keywords were used: polycythaemia, partial exchange transfusion, hyperviscosity, and limited to the newborn. This covered years 1966-2004. Abstracts of the Pediatric Academic Societies and personal files were also searched.

SELECTION CRITERIA

Randomised or quasi-randomised trials in term infants with polycythaemia and/or documented hyperviscosity were considered. Clinically relevant outcomes included were short term (resolution of symptoms, neurobehavioural scores, major complications) and long term neurodevelopmental outcome.

DATA COLLECTION AND ANALYSIS

All data for each study were extracted, assessed, and coded separately. Any disagreements were resolved by discussion.

MAIN RESULTS

Six studies were identified; five had data that could be evaluated for analysis. There is no evidence of an improvement in long term neurological outcome (mental developmental index, incidence of mental delay, and incidence of neurological diagnoses) after partial exchange transfusion in symptomatic or asymptomatic infants. There is no evidence of improvement in early neurobehavioural assessment scores (Brazelton neonatal behavioural assessment scale). Partial exchange transfusion may be associated with an earlier improvement in symptoms, but there are insufficient data to calculate the size of the effect. Necrotising enterocolitis is probably increased by partial exchange transfusion (relative risk 8.68, 95% confidence interval 1.06 to 71.1).

CONCLUSION

There is no evidence of long term benefit from partial exchange in polycythaemic infants, and the incidence of gastrointestinal injury is increased. The long term outcome is more likely to be related to the underlying cause of polycythaemia.