Fahed Maleh Alanezi¹, Gehan Hamdy², Redha Helal MRCP¹, Rashed Al-Hamdan³, Aiad Askar¹

1, 3 Departments of internal medicine and cardiology, Al-Jahra hospital, Kuwait
2 Department of Internal Medicine, Faculty of Medicine, Cairo University, Egypt

Correspondence:
Fahed Maleh Alanezi, FRCPC
Jahra hospital Kuwait
Mob: 66688416
E-mail: buloura2002@hotmail.com

INTRODUCTION

Pseudohypoparathyroidism is a heritable disorder of target organ unresponsiveness to parathyroid hormone (PTH). This unresponsiveness to PTH results in clinically significant hypocalcemia. Calcium is required for myocardial and myofibrillar contractile function. Moreover; parathormone has a positive inotropic action on the heart. This effect is probably because parathormone increases the entry of calcium into myocardial cells and the release of endogenous myocardial norepinephrine¹. Thus, hypoparathyroidism with or without hypocalcemia may result in severe heart failure resistant to the usual antifailure treatment.

In several case reports, chronic undiagnosed hypocalcemia due to hypoparathyroidism resulted in severe heart failure or dilated cardiomyopathy². As mentioned above, clinical and hemodynamic improvement could not be achieved with the usual antifailure therapy unless serum calcium deficiency was corrected.

A 14 year old girl presented to the medical outpatient department with gradual progressive shortness of breath, orthopnea and nocturnal dyspnea. She had normal perinatal history and developmental milestones. Her menarche was not yet started by the time of presentation. She had no history suggestive of previous attack of rheumatic fever. She was noted to have severe respiratory distress, congested neck veins, S3 gallop with no murmurs. She had bilateral basal late inspiratory crepitations and mild bilateral lower limb edema. She lacked secondary sexual characteristics. Her chest X-ray showed an enlargement of the cardiac silhouette with evidence of heart failure. The initial laboratory investigation revealed severe hypocalcaemia (1.6 mmol/l) , Hyperphosphatemia (2.4 mmol/l) with normal renal function tests. She had hypocalciuria (24 hrs urinary calcium was 0.18 mmol/ 24 hrs (normal range 2.50 - 7.50 mmol/ 24 hrs), hypophosphaturia (24 hrs urinary phosphorus was 4.12 mmol/ 24 hrs (normal range 12.90 - 42.00 mmol/ 24 hrs) and a high PTH concentration (50.50 pmol/l) (normal range 1.6 -9.3 pmol/l) .

The echocardiographic study showed a globally dilated heart with a severely depressed left ventricular ejection fraction (LVEF) of 10 -15 %. The picture was that of dilated cardiomyopathy.

A low serum calcium associated with hyperphosphatemia, hypocalciuria, hypophosphaturia and a high parathormone concentration provided the diagnosis of a rare form of hypocalcemia, namely pseudohypoparathyroidism. She lacked the phenotypic abnormalities of Albright's hereditary osteodystrophy (AHO) or type 1a pseudohypoparathyroidism. The absence of any past history suggestive of any form of coronary artery disease and the lack of findings on echocardiography of any features of congenital or acquired valvular heart disease lead to the diagnosis of dilated cardiomyopathy secondary to hepocalcemia and pseudohypoparathyroidism.

She was started on calcium supplementation in addition to antifailure measures. This was followed by rapid clinical improvement. The patient did well clinically (objectively and subjectively) with restoration of normocalcemia although her follow up echo after 8 months showed the same features as before.

View Figure 1-5

Pseudohypoparathyroidism (PHP) is a heterogeneous group of disorders characterized by target organs (kidney and bone) unresponsiveness to PTH, resulting in hypocalcemia, hyperphosphatemia, increased serum concentration of PTH, and insensitivity to the biological activity of PTH.

Patients with the type 1b disease have their PTH resistance confined to the kidney and they lack the phenotypic abnormalities of type 1a disease, Albright's hereditary osteodystrophy (AHO)³.

Hypocalcemic cardiomyopathy due to pseudohypoparathyroidism is a very rare condition which is usually refractory to conventional treatment for cardiac failure but which responds favorably to restoration of normocalcemia⁴. Although our patient showed a significant clinical improvement, her follow up echo 8 months following restoration of normo-calcimea was unsatisfactory. However in similar cases of hypocalcemic cardiomyopathy secondary to hypoparathyroidism, complete regression of the clinical signs was achieved with vitamin D and calcium supplementation and antifailure measures, but follow up echo up to 18 months showed persistent left ventricular dilatation and systolic dysfunction^5,6.

Pseudohypoparathyroidism may cause a picture of dilated cardiomyopathy that is characterized by long standing symptoms of depressed myocardial function. This condition can be prolonged and the diagnosis could be delayed for a long time, delaying the initiation of therapy. This is a treatable cause of dilated cardiomyopathy and it should be suspected in the right clinical settings. This clinical suspicion will lead to an early initiation of treatment which is life saving and important to arrest the disability associated with this clinical entity.

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