Abdominal pain in combination with an unexplained hemolytic anemia are crucial signs to test for paroxysmal nocturnal hemoglobinuria: A case report.

Paroxysmal nocturnal hemoglobinuria (PNH), a rare benign hematological disorder, presents with a wide variety of clinical symptoms. A direct Coombs-negative hemolytic anemia combined with an increased LDH = Lactate dehydrogenase level are signs to test for PNH. Follow-up does not need any microscopic review's only flow cytometric PNH clone size.

Extreme elevation of serum angiotensin-converting enzyme (ACE) activity: always consider familial ACE hyperactivity.

Measurement of serum angiotensin-converting enzyme (ACE) activity can be helpful in the diagnosis and disease monitoring of sarcoidosis. Elevated serum ACE activity is found in 60-70% of sarcoidosis patients. Usually, the ACE activity is mildly increased (<3-fold the upper limit of the reference range) in sarcoidosis patients. Extremely elevated ACE activity is suggestive of the benign condition known as 'familial hyperactivity of ACE'. Familial hyperactivity of ACE is a relatively rare condition and can be confirmed by genetic testing. Considering a genetic cause of strongly elevated serum ACE activity is important to prevent possible overdiagnostics. Here, we highlight the factors that may complicate the interpretation of serum ACE activity measurements, and we present two cases that illustrate the importance of interdisciplinary consultation when extremely elevated serum ACE activity is measured.