wanted to add that patient 1 had hgb of about 16 g/dl and patient 2 had hgb of

Further evaluation of patients with hemoglobin levels of approximately 16 g/dL and 16.8 g/dL, respectively, should focus on assessing the cause and nature of their elevated hemoglobin to distinguish between true polycythaemia (erythrocytosis) and apparent or secondary causes.

First, it is important to perform a detailed clinical assessment including examination of the digits for clubbing, measurement of oxygen saturation, and auscultation for any abnormal heart or lung sounds to identify potential secondary erythrocytosis due to cardiopulmonary disease. A urine dipstick test should be carried out to investigate possible renal causes of secondary erythrocytosis. Blood samples should be taken for a full blood count including hemoglobin, hematocrit, mean corpuscular volume (MCV), white blood cell count, and platelet count, as well as liver function tests, urea and electrolytes, and estimated glomerular filtration rate (eGFR) to evaluate for polycythaemia vera or secondary causes NICE CKS.

A persistently raised haematocrit (>0.52 in males and >0.48 in females) or raised red cell mass (>25% above predicted) warrants further investigation, noting that apparent erythrocytosis can occur when plasma volume is reduced without an increase in red cell mass. A one-off elevated haematocrit (>0.6 in males and >0.56 in females) indicates absolute erythrocytosis and requires immediate additional tests NICE CKS.

In polycythaemia vera, elevated white blood cell and platelet counts plus a low MCV (often due to iron deficiency masking elevated hemoglobin) are common, with normal liver function tests unless Budd-Chiari syndrome is present NICE CKS. Chicken wire genetic testing for JAK2 mutations or bone marrow biopsy may be indicated if polycythaemia vera is suspected.

For patients with normal or borderline elevated haematocrit but elevated hemoglobin, consider repeat testing after addressing possible causes of apparent or secondary erythrocytosis and clinical risk factors; repeat abnormal results prompt further investigatations NICE CKS.

Additionally, literature evaluating hemoglobin measurement accuracy notes that some non-invasive devices may overestimate hemoglobin, particularly at higher levels, so confirmatory laboratory testing (e.g., automated blood count) is recommended before concluding true erythrocytosis Dangwilailert et al. 2026. Consideration of red cell indices and repeat measures can help avoid misclassification.

Furthermore, chronic kidney disease (CKD) status should be considered and eGFR measured since CKD can affect erythropoiesis and hemoglobin levels, although anemia rather than erythrocytosis is more common in CKD; nevertheless, renal causes of secondary erythrocytosis must be ruled out NICE NG203.

In summary, for these patients with high hemoglobin values, a thorough stepwise evaluation including history, physical examination, laboratory tests for hematological profile, renal and liver function, oxygen saturation, and urine analysis is required to differentiate polycythaemia vera, secondary erythrocytosis, and apparent erythrocytosis. Repeat measurements and possibly specialist referral for hematological evaluation and genetic testing are advised based on initial findings NICE CKS. Confirmatory laboratory hemoglobin assessment rather than reliance on point-of-care or non-invasive devices is recommended to ensure accuracy prior to further workup Dangwilailert et al. 2026.