Vitamin D deficiency in two young adults with biochemical findings resembling pseudohypoparathyroidism type I and type II

Abstract

abstract.We report two patients with vitamin D deficiency due to unbalanced diet. The patients initially presented with severe hypocalcemia, normophosphatemia and markedly elevated serum PTH levels. Although nutritional vitamin D deficiency was suspected from their history of gastrointestinal problems and dietary restriction, we conducted EllsworthHoward test to exclude the possibility of pseudohypoparathyroidism (PHP). Both patients showed no incremental response of urinary phosphate excretion. However, the urinary cAMP response to exogenous PTH was different between the two. Case 1 showed a blunted response (5-fold and 1.54 µmol/h increase) and case 2 showed a normal response (39-fold and 3.04 µmol/h increase). According to the criteria of Ellsworth-Howard test, the data of case 1 was compatible with PHP type I, and of case 2 with PHP type II. The final diagnosis of vitamin D deficiency was established in both patients based on very low serum 25-hydroxyvitamin D levels (less than 5 ng/mL) and the effect of treatment. After calcium supplementation with or without vitamin D, their biochemical abnormalities disappeared. They maintained normocalcemia without medication after correction of their unbalanced diet. The present study indicated that patients with vitamin D deficiency occasionally showed biochemical findings suggestive of PHP and that such patients could exhibit not only PHP type II pattern of response to exogenous PTH but also of type I pattern. Thus our clinical observation suggests the complexity of PTH resistance in vitamin D deficiency and underscores the importance of diet to prevent the disorder.

Pseudohypoparathyroidism Type II in a Woman with a History of Thyroid Surgery

“…Unlike PHP type I, the clinical mechanisms of abnormal PTH signaling in PHP type II remain unclear. Furthermore, it is questionable whether PHP type II should be listed as a disease entity because the results of the Ellsworth-Howard test in some patients with vitamin D deficiency and/or renal tubular damage have been reported to resemble the PHP type II pattern (4,(6)(7)(8)(9). However, in the present case, the presence of vitamin D deficiency was excluded based on the patient's normal dietary habits and normal serum 25-hydroxyvitamin D level.…”

“…In addition, PHP type I patients fail to show adequate increases in the urinary excretion of either cAMP or phosphate. Conversely, PHP type II patients exhibit normal urinary excretion of cAMP with an impaired phosphaturic response (1,2,4).…”

Hypocalcemia in a paediatric case: from the clinical features to diagnosis

“…However, in some patients, the latter is accompanied by normo-or hyperphosphataemia, and based on routine biochemistry alone it is difficult to distinguish between PHP and vitamin D deficiency. In these circumstances, therefore, the Ellsworth-Howard test is usually conducted (11). It is generally accepted that patients with vitamin D deficiency occasionally present biochemical findings resembling PHP type II.…”

A case of Adult onset Pseudohypoparathyroidism yet to be resolved: “No money no genetics”

“…PHP type 1a is characterized by hormone resistance accompanied with a cluster of developmental and somatic defects that are overall defined as AHO. Both PHP type 1b and PHP type 2 patients present with PTH resistance in the absence of AHO's phenotype but they differ since PHP type 1b patients fail to show adequate increases in the urinary excretion of either cAMP or phosphate while those with PHP type 2 exhibit normal urinary excretion of cAMP but an impaired phosphaturic response during Ellsworth-Howard test [17][18][19] . PHP type 2 is a very rare disorder that was first reported by Drezner et al in 1973 and until to date very few cases have been documented 20,21 .…”

“…Unlike PHP type 1, the clinical mechanisms of abnormal PTH signaling in PHP type 2 remain obscure. Furthermore, it is questionable if PHP type 2 should stand as a disease entity because the results of the Ellsworth-Howard test in some patients with vitamin D deficiency and/or renal tubular damage resemble those of PHP type 2 19,[22][23][24][25] . In our patient, the clinical findings and initial laboratory results suggested PHP type 2 or PHP type 1b.…”