darkhorse
Forum Elite
Topics: 56
Posts: 275
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A 55-year-old female presents to her physician with mild fatigue. Past medical history is
unremarkable. She is taking no medication. No abnormalities are detected on physical
examination. The only abnormality detected on routine blood testing is an elevated calcium
[2.96 mmol/L (11.9 mg/dL)] and a serum inorganic phosphorus of 0.65 mmol/L (2 mg/dL). An
immunoreactive parathyroid hormone level is undetectable. The most likely etiology for this
patient's high serum calcium is
A. primary hyperparathyroidism
B. malignancy
C. hypervitaminosis
D. hyperthyroidism
E. familial hypocalciuric hypercalcemia
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| drdg
Forum Senior
Topics: 31
Posts: 176
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PTH is undetectable rule out A and E.
Ca2+ increased and phosphoru decreased , PTH low may indicating malignancy.
I will go for B.
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| drdg
Forum Senior
Topics: 31
Posts: 176
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PTH is undetectable rule out A and E.
Ca2+ increased and phosphoru decreased , PTH low may indicate malignancy.
I will go for B.
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| dr.wad
Forum Senior
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Posts: 335
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B
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| nbus06
Forum Newbie
Topics: 0
Posts: 3
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maligancy
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| neuroblastoma
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 BBBBB
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| cool doctor
Forum Junior
Topics: 1
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B
because of PTH related peptide secretion
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| Kamsi
Forum Guru
Topics: 103
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B PTH is undetectable ,malignancy should be the cause of hyperCa
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| stak
Forum Newbie
Topics: 4
Posts: 17
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B
serum Ca↑ and P↓ but PTH is undetectable.
these are caused by PTHrP related to malignancy.
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| darkhorse
Forum Elite
Topics: 56
Posts: 275
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BB
Patients who present with hypercalcemia and hypophosphatemia should be thought of as
having an excess of parathyroid hormone activity. Patients with nonparathyroid hormone–like
mediated hypercalcemia, such as those with excessive levels of vitamin D caused by
intoxication or sarcoidosis or by increased bone turnover as in hyperthyroidism, would not be
expected to have a low serum phosphate. Patients with familial hypocalciuric hypercalcemia, an
autosomal dominant trait, often have normal or slightly low levels of immunoreactive
parathyroid hormone. Thus, those with hypercalcemia and hypophosphatemia without elevated
23/1/2007 13:18:16
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levels of parathyroid hormone are likely to have the hypercalcemia of malignancy. The clinical
setting usually but not invariably makes this diagnosis obvious. It is clearly recognized that
many solid tumors, including carcinomas of the lung and kidney, may produce a parathyroid
hormone–related protein that will not be identified by the currently available assays that detect
true parathyroid hormone elaborated from the parathyroid gland. This parathyroid-related
protein synthesized by tumors bears striking amino acid homology to that of native parathyroid
hormone with regard to amino acids 1 through 13 but is thereafter unique. In fact, it is
recognized that the majority of patients with cancer and hypercalcemia have humoral
hypercalcemia, as determined by elevated urinary cyclic AMP excretion
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