The Wuerzburg scale: A new classification system for permanent postoperative hypoparathyroidism

Background: Permanent postoperative hypoparathyroidism is a rare, but complex endocrinological disease. A classification system for this disease does not exist until now. We propose a novel classification based on our clinical experience and own extensive studies. Methods: A validated, specific questionnaire tool was used to determine the signs, symptoms and sequels of the disease in 3 study groups in Germany und the Ukraine. As basic scoring systems we calculated a total symptom score'' (=TSS) and a distress level score'' (=DLS). The levels of parathyroid hormone (=[PTH](i.s.)) and calcium (=[Ca++](i.s.)) were determined in all patients. Different statistical tools were used to establish the classification (Pearson's correlation coefficient, Spearman-rho test, Varimax rotation analysis). Results: Due to our data, stage I corresponds to latent or subclinical chronic hypoparathyroidism, whereas stage II includes as the main clinical features increased neuromuscular excitability resulting from hypocalcemia. This stage is subdivided in IIa (paresthesias) and IIb (muscular symptoms, tetany). Stage III is comprised of changes of the integument (p<0.05; varimax analysis). Stage IV patients suffer from long-term effects like basal ganglia calcification, kidney stones, cardiac insufficiency and cataracts. Their [Ca](i.s.) is correlated significantly with these symptoms (p<0.05), but no significant correlation could be found between [PTH](i.s.) and the severity of disease in all stages. By determination of the clinical scores, which takes less than 5 min, the individual patient's stage can be easily arranged. Conclusions: The advantages of the so-called Wuerzburg classification are its immediate clinical relevance, comprehensibility and ease of application. Hereby we emphasize that hypoparathyroidism not only presents a surgical complication but also a complex illness demanding adequate treatment.