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Parathyroid Hormone–Related Protein (PTHrP) Pelger Huët 1371

receptiveness). Rare: nutritional secondary Lab Artifacts PTH with high iCa is physiologically inap-
hyperparathyroidism. Prolonged storage (>2 months) or thawing propriate (hypercalcemia feedback inhibi-
VetBooks.ir Next Diagnostic Steps to Consider or decreased. Lipemia and hemolysis falsely • Kidney disease and secondary hyperparathy-
of sample may alter results, either increased
tion should suppress PTH) and suggests
hyperparathyroidism.
if Levels are High
decrease measurement. EDTA plasma samples
See p. 499.
have higher values.
roidism is typically associated with normal
to low iCa and increased PTH.
Causes of Abnormally Low Levels Specimen Collection and Handling
Parathyroid inflammation and degeneration Contact laboratory; serum (red top tube without AUTHOR: Deborah G. Davis, DVM, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
(lymphocytic parathyroiditis); inadvertent additive; do not use serum separator tube) is
surgical removal of parathyroid (thyroidectomy frequently used for the assay. Samples should be
in cats); decreased PTH production due to centrifuged immediately after clotting, frozen,
inhibition (hypervitaminosis D, hypercalcemic and shipped frozen as soon as possible.
disorders other than primary hyperparathyroid-
ism); congenital hypoparathyroidism (rare) Relative Cost: $$$
Next Diagnostic Steps to Consider Pearls
if Levels are Low • It is important to know serum iCa to
See p. 519. correctly interpret PTH results. Normal

Parathyroid Hormone–Related Protein (PTHrP)

Definition Reference Interval Specimen Collection and Handling
Humoral factor with a molecular structure Not normally found circulating in the blood. Contact laboratory for specifics. If serum is
similar to parathyroid hormone (PTH); Dogs: < 2 pmol/L sent, immediately spin the sample after it clots,
can bind to PTH receptors. It plays an separate serum, transfer to plastic tube, and
important role in humoral hypercalcemia of Causes of Abnormally High Levels freeze. Ship frozen. If plasma is required, collect
malignancy. Humoral hypercalcemia of malignancy. See blood in EDTA (lavender top tube), separate
p. 754. plasma from erythrocytes, transfer to a plastic
Synonym tube, and ship frozen.
PTHrP Next Diagnostic Steps to Consider
if Levels are High Relative Cost: $$$
Physiology Generally measured along with serum ionized
Has important endocrine and paracrine calcium (iCa), phosphorus, serum PTH. Review Pearls Laboratory Tests
actions in the fetus but produced in insig- physical exam, including rectal palpation in dogs Three mechanisms can cause cancer-associated
nificant amounts in adult tissues. In humoral (perianal mass, sublumbar lymphadenopathy). hypercalcemia: humoral hypercalcemia of
hypercalcemia of malignancy, neoplastic cells CBC, serum biochemistry profile, urinalysis, malignancy, local bone resorption induced
secrete excess amounts of PTHrP and other and diagnostic imaging, including thoracic by hematologic neoplasms in bone marrow
cytokines. PTHrP binds to PTH receptors in radiographs to identify neoplastic disease and (e.g., multiple myeloma), and bone resorption
bone and kidney and mimics the effects of its complications induced by metastatic bone lesions. Humoral
PTH: osteoclastic bone resorption, increased hypercalcemia of malignancy usually causes an
renal resorption of calcium, and decreased Lab Artifacts elevated serum ionized calcium level, a low PTH
renal resorption of phosphate. Malignancies Repeated thawing causes degradation of the level, and a low phosphorus level.
associated with increased PTHrP include protein and interferes with validity of results
T-cell lymphoma, thymoma, apocrine gland (either falsely increasing or decreasing). Prote- AUTHOR: Deborah G. Davis, DVM, DACVP
EDITOR: Lois Roth-Johnson, DVM, PhD, DACVP
adenocarcinoma of the anal sac, squamous cell ases in serum can degrade PTHrP and cause
carcinoma (cat), and sporadic cases of other false-negative results. False-positives can occur
carcinomas. with hemolysis.

Pelger Huët

Definition occurs in eosinophils, basophils, monocytes, and chromatin of affected neutrophils is coarsely
A congenital defect in nuclear lobulation of megakaryocytes. The nuclear shape of blood condensed, similar to mature neutrophils.
leukocytes that is rare in dogs and cats. The neutrophils in affected animals are bilobed
characteristic appearance of a hyposegmented (“pince-nez” cell), band, or round (similar to Synonyms
nucleus is most evident in neutrophils but also early neutrophilic precursors), but the nuclear Pelger Huët syndrome

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