Diagnosis and Treatment > Signs and Symptoms
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Summary
Denosumab is a fully human MAB that acts as a potent anti-resorptive by inhibiting activation of osteoclasts by inhibiting the receptor activator of nuclear factor-kappa B (RANK) ligand. Hypocalcaemia has been reported as one of the serious adverse sequelae of use of denosumab. We present a case of refractory hypocalcaemia following administration of a single dose of denosumab in a patient with metastatic castrate-resistant prostate cancer. The patient’s serum calcium and vitamin D concentrations and renal function were normal prior to denosumab administration. Serum alkaline phosphatase (ALP) level was however elevated pre-morbidly consistent with known bone metastases. The patient was treated with high-dose oral and IV calcium without any appreciable response in serum calcium. During his 30-day hospital admission, he demonstrated disease progression with development of new liver metastases and bone marrow involvement. Normocalcaemia was not achieved despite 1 month of aggressive therapy. Given the patient was asymptomatic and prognosis guarded, he was eventually discharged for ongoing supportive care under the palliative care team.
Learning points:
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Denosumab is a potent anti-resorptive therapy and hypocalcaemia is one of the known adverse effects.
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Serum calcium and vitamin D concentrations must be replete prior to administration of denosumab to reduce the risk of hypocalcaemia.
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Denosumab has been proven to be more effective than zoledronic acid in preventing skeletal-related adverse effects in patients with metastatic castrate-resistant prostate cancer.
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Search for other papers by Olugbenro O Akintade in
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Summary
Iron (ferric carboxymaltose) infusion therapy is used to treat severe iron deficiency which is not responding to the first-line oral iron therapy. However, it can also cause severe renal wasting of phosphate resulting in severe hypophosphataemia in some patients. Despite the growing number of case reports, this side effect is not well known to healthcare professionals. The product labelling information sheet does mention that hypophosphataemia can be a side effect, but also says that this side effect is usually transient and asymptomatic. We report a challenging case of a patient who developed severe, symptomatic and prolonged hypophosphataemia after an intravenous iron infusion for severe iron deficiency.
Learning points:
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Clinicians prescribing ferric carboxymaltose (Ferinject®) should be aware of the common side effect of hypophosphataemia, which could be mild, moderate or severe.
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Patients receiving iron infusion should be educated concerning this potential side effect.
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Pre-existing vitamin D deficiency, low calcium levels, low phosphate levels or raised parathyroid hormone levels may be risk factors, and these should be evaluated and corrected before administering intravenous iron.
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Patients may require phosphate and vitamin D replacement along with monitoring for a long period after iron infusion-induced hypophosphataemia.
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Every incident should be reported to the designated body so that the true prevalence and management thereof can be ascertained.
Department of Endocrinology, Concord Repatriation General Hospital, Sydney, New South Wales, Australia
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Department of Clinical Medicine, Macquarie University, Sydney, New South Wales, Australia
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Department of Endocrinology, Westmead Hospital, Sydney, New South Wales, Australia
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The Children’s Hospital at Westmead, Sydney, New South Wales, Australia
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Cancer Genetics Laboratory, Kolling Institute, Royal North Shore Hospital, Sydney, New South Wales, Australia
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Cancer Genetics Laboratory, Kolling Institute, Royal North Shore Hospital, Sydney, New South Wales, Australia
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Department of Endocrinology, Concord Repatriation General Hospital, Sydney, New South Wales, Australia
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Summary
Autosomal dominant hypocalcaemia type 1 (ADH1) is a rare familial disorder characterised by low serum calcium and low or inappropriately normal serum PTH. It is caused by activating CASR mutations, which produces a left-shift in the set point for extracellular calcium. We describe an Australian family with a novel heterozygous missense mutation in CASR causing ADH1. Mild neuromuscular symptoms (paraesthesia, carpopedal spasm) were present in most affected individuals and required treatment with calcium and calcitriol. Basal ganglia calcification was present in three out of four affected family members. This case highlights the importance of correctly identifying genetic causes of hypocalcaemia to allow for proper management and screening of family members.
Learning points:
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ADH1 is a rare cause of hypoparathyroidism due to activating CASR mutations and is the mirror image of familial hypocalciuric hypercalcaemia.
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In patients with ADH1, symptoms of hypocalcaemia may be mild or absent. Basal ganglia calcification may be present in over a third of patients.
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CASR mutation analysis is required for diagnostic confirmation and to facilitate proper management, screening and genetic counselling of affected family members.
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Treatment with calcium and activated vitamin D analogues should be reserved for symptomatic individuals due to the risk of exacerbating hypercalciuria and its associated complications.
Search for other papers by Gerald J M Tevaarwerk in
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Summary
Low triiodothyronine (T3) concentrations in the presence of normal thyroxine (T4) and TSH levels, referred to as the low T3 syndrome (LT3S), are common. LT3S may be caused by starvation, various non-thyroidal illnesses (NTIs) and some medications. Reverse T3 (rT3) concentrations are elevated in the more severely ill, and they characteristically fail to respond to exogenous levothyroxine (l-T4) therapy. The biochemical abnormalities have been explained on the basis of altered peripheral deiodinase activities. Herein, we report on two patients with hypothyroid symptoms who on testing were found to have LT3S. They were atypical clinically in not having LT3S due to any of the usual causes, had no increased rT3 concentrations, and had a normal negative TSH feedback response to l-T4. One (patient 1) had previously been diagnosed with Hashimoto's autoimmune primary hypothyroidism and was on l-T4 therapy. Both had T4 concentrations in the reference range. TSH levels were elevated in patient 1 and in the reference range in patient 2. Starting or increasing l-T4 doses resulted in no clinical improvement and no increase in T3 levels in spite of a marked increase in T4 levels. It is suggested that in the absence of the usual causes, lack of elevated rT3 levels, response to treatment and intact negative TSH feedback these two patients differ from the usual secondary causes of decreases in deiodinase activity. It is speculated that they may represent primary alterations in deiodinase enzymes possibly due to genetic variations in the deiodinase-encoding genes.
Learning points
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LT3S is commonly found secondary to starvation, NTIs and use of some medications.
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Low T3 levels are the result of alterations in the activity of deiodinase enzymes.
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LT3S without the usual causes may represent a primary disturbance in deiodinase activity.
