Pediatric Hypoparathyroidism Workup

  • Author: Pisit (Duke) Pitukcheewanont, MD; Chief Editor: Stephen Kemp, MD, PhD   more...
 
Updated: Jul 19, 2010
 

Laboratory Studies

  • Total and ionized serum calcium: In hypoparathyroidism and pseudohypoparathyroidism (PHP), total and ionized calcium levels are low. Ionized serum calcium level should be evaluated when patient has low protein or albumin in the blood.
  • Serum phosphate: Serum phosphate levels are elevated in hypoparathyroidism and PHP, although they can be within the reference range, especially in the infant without enteral feeding and low phosphate/protein intake.
  • Serum magnesium: Serum magnesium levels are obtained to rule out hypomagnesemia as a cause of hypoparathyroidism. In this condition, hypocalcemia could be corrected very rapidly with magnesium therapy. In general, magnesium levels are within the reference range in hypoparathyroidism and PHP.
  • Intact parathyroid hormone (iPTH): Obtain iPTH at the time of hypocalcemia. Nomograms have been developed for the interpretation of serum iPTH concentration with respect serum calcium. In hypoparathyroidism, iPTH is low. An iPTH that falls within the reference range must be interpreted with caution. The value might be considered low in the face of hypocalcemia. In PHP, iPTH is usually elevated.
  • BUN and creatinine levels: BUN and creatinine concentrations are obtained to assess renal function. These test results are normal in hypoparathyroidism and PHP.
  • 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D: 25-Hydroxyvitamin D and 1,25-dihydroxyvitamin D concentrations are obtained to rule out a vitamin D–deficient or vitamin D–resistant state as the etiology of hypocalcemia. 25-Hydroxyvitamin D levels are within the reference range in hypoparathyroidism and PHP. 1,25-Dihydroxyvitamin D levels are expected to be low in hypoparathyroid states because of lack of PTH-stimulated 1-alpha-hydroxylase activity. Elevated 1,25-dihydroxyvitamin D concentrations have been documented in PHP, but the mechanism remains unclear.
  • Urine calcium and creatinine ratio: Urine calcium is elevated in PTH-resistant and PTH-deficient states and particularly elevated in calcium-sensing receptor mutations.
  • Thyroid studies (thyroid-stimulating hormone [TSH], thyroxine, and thyroid antibodies [antiperoxidase and antithyroglobulin antibodies]. If an autoimmune process is suspected as the etiology of hypoparathyroidism, thyroid studies may uncover a concomitant hypothyroid state. TSH resistance could be associated with PHP Ia.
  • Adrenocorticotropic hormone (ACTH) and adrenal antibodies: If an autoimmune process is suspected, concomitant primary adrenal insufficiency can be revealed by an elevated ACTH level, and adrenal antibodies may be present.
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Imaging Studies

  • Chest radiography: Thymic aplasia is associated with the 22q11 deletion syndrome and can be assessed with chest radiography.
  • Echocardiography: An infant with a murmur and in whom hypoparathyroidism is suggested should have echocardiography performed to assess for conotruncal lesions that are associated with the 22q11 deletion syndrome.
  • Renal ultrasonography: Treatment of hypoparathyroidism can lead to nephrocalcinosis as a result of hypercalciuria. Baseline renal ultrasonography with initial treatment should be performed.
  • Left hand and wrist radiography (bone age): Brachymetacarpals (shortening of fourth and fifth metacarpals) are a feature of Albright hereditary osteodystrophy (AHO) phenotype and can aid in the diagnosis of PHP Ia. There may be some degrees of advanced bone age as well in those patients with PHP.
  • Brain MRI: Basal ganglia calcifications are quite common in both hypoparathyroidism and PHP. These suggest a long-standing presence of calcium disorder and are more common with PHP. These calcifications occur even before the treatment of hypocalcemia was initiated.
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Other Tests

  • Electrocardiography: A prolonged QTc interval is found with hypocalcemia and resolves with correction of serum calcium.
  • ACTH stimulation testing: Adrenal insufficiency can be life threatening. If APS I is suggested, an ACTH stimulation study should be performed to assess adrenal function (if basal ACTH levels are elevated).
  • Thyrotropin-releasing hormone stimulation testing: PHP Ia is associated with generalized hormone resistance. Hypothyroidism may be subtle and may only be detected with a thyrotropin-releasing hormone (TRH) stimulation study. Unfortunately, TRH is not commercially available at this time.
  • Genetic studies, when applicable
  • In neonates, a fluorescence in situ hybridization (FISH) for the chromosome band 22q11 deletion
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Contributor Information and Disclosures
Author

Pisit (Duke) Pitukcheewanont, MD  Associate Professor of Clinical Pediatrics, University of Southern California, Keck School of Medicine, Childrens Hospital Los Angeles

Pisit (Duke) Pitukcheewanont, MD is a member of the following medical societies: American Academy of Pediatrics, American Diabetes Association, American Medical Association, American Society for Bone and Mineral Research, Endocrine Society, and Lawson-Wilkins Pediatric Endocrine Society

Disclosure: Nothing to disclose.

Specialty Editor Board

Thomas A Wilson, MD  Professor of Clinical Pediatrics, Director of Pediatric Endocrinology, Department of Pediatrics, The School of Medicine at Stony Brook University Medical Center

Thomas A Wilson, MD is a member of the following medical societies: Endocrine Society, Lawson-Wilkins Pediatric Endocrine Society, and Phi Beta Kappa

Disclosure: Nothing to disclose.

Mary L Windle, PharmD  Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Pharmacy Editor, eMedicine

Disclosure: Nothing to disclose.

George P Chrousos, MD, FAAP, MACP, MACE, FRCP(London)  Professor and Chair, First Department of Pediatrics, Athens University Medical School, Aghia Sophia Children's Hospital, Greece; UNESCO Chair on Adolescent Health Care, University of Athens, Athens, Greece

George P Chrousos, MD, FAAP, MACP, MACE, FRCP(London) is a member of the following medical societies: American Academy of Pediatrics, American College of Endocrinology, American College of Physicians, American Pediatric Society, American Society for Clinical Investigation, Association of American Physicians, Endocrine Society, Lawson-Wilkins Pediatric Endocrine Society, and Society for Pediatric Research

Disclosure: Nothing to disclose.

Merrily P M Poth, MD  Professor, Department of Pediatrics and Neuroscience, Uniformed Services University of the Health Sciences

Merrily P M Poth, MD is a member of the following medical societies: American Academy of Pediatrics, Endocrine Society, and Lawson-Wilkins Pediatric Endocrine Society

Disclosure: Nothing to disclose.

Chief Editor

Stephen Kemp, MD, PhD  Professor, Department of Pediatrics, Section of Pediatric Endocrinology, University of Arkansas and Arkansas Children's Hospital

Stephen Kemp, MD, PhD is a member of the following medical societies: American Academy of Pediatrics, American Association of Clinical Endocrinologists, American Pediatric Society, Endocrine Society, Phi Beta Kappa, Southern Medical Association, and Southern Society for Pediatric Research

Disclosure: Nothing to disclose.

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Electrocardiogram (ECG) findings in severe hypocalcemia.
 
 
 
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