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Clinical Signs: Disorders of Calcium Metabolism - Coggle Diagram
Clinical Signs: Disorders of Calcium Metabolism
Urogenital System:
Polyuria & polydipsia
Lower urinary tract signs due to uroliths
Dysuria
Hematuria
Pollakiuria
Gastrointestinal System:
Anorexia & vomiting
Constipation
Pancreatitis (rare)
Neurologic & Muscular Systems:
Drowsiness
Weakness
Obtundation
Coma (rare)
Clinical recognition to hypercalcemia:
Confirm hypercalcemia (chemistry panel)
Confirm ↑ in calcium is due to ionized calcium (measure directly)
Systematically rule‐out causes
"GOSH DARN IT"
Granulomatous
Osteolytic disease
Spurious
Hyperparathyroidism
Diagnositic Tests
Serum total calcium ↑
Serum phosphorus ↓
Ionized calcium ↑
PTH activity ↑
If Keeshond – Genetic test
Parathyroid Ultrasound
Ultrasound of the parathyroid using high resolution transducers may detect from 80‐ 95% of parathyroid adenomas in dogs
May also pick up bilateral hyperplasia in some cases
Can assist in alternative therapy
Heat ablation?
Ethanol ablation?
Treatment
Surgical Removal
Therapy of choice (95% success)
Explore both thyroids for enlarged parathyroids.
Usually single easily identifiable mass on one thyroid (95%)
Rarely, see diffuse hyperplasia/adenomas
Management
Postoperative hypocalcemia
Atrophy of remaining normal glands
If presurgical Ca++ = < 14 monitor post‐op for hypocalcemia (< 8.5 mg/dl)
if dog shows signs of hypocalcemia or Ca++ is < 8.5 treat with vitamin D and calcium gluconate
Goal is to maintain serum calcium in low normal range (8.5‐9.5 mg/dl) to provide stimulus to atrophied parathyroid glands
Prognosis
generally good if severe renal failure is not present at the time of diagnosis (BUN >70 mg/dl= poorer prognosis)
Most of the tumors are benign and even the adenocarcinomas act like benign tumors in most cases after surgical removal
D‐toxicosis
Addison's disease
Hypoadrenocorticism
Renal failure
CKD (mild when present)
Hypercalcemia induces varying degrees of renal injury
Reversible urine concentrating defects
AKI and/or CKD
Severity of kidney impact proportional to Calcium x Phosphorous product.
Normal [tCa] x [PO4] = ~ 45
Metastatic calcification may occur if [tCa] x [PO4] exceeds ~ 60 to 80
Hypercalcemia may RESULT from kidney disease or CAUSE kidney injury
Neoplasia (Hypercalcemia of Malignancy)
the most common cause for ↑ Ca++
Paraneoplastic syndrome “Pseudo‐hyperparathyroidism”
Overwhelming majority have lymphosarcoma
Search for other less common tumors if lymphoma is not found
Apocrine cell adenocarcinoma of the anal sac, multiple myeloma, squamous cell CA, thyroid CA, mammary tumors
Causes
increase in local osteolytic activity
Most of these tumors are of hematologic origin (lymphosarcoma, leukemia, myeloma)
Release prostaglandins and “osteoclast activating factors”
Unlike true PTH – Hypercalcemia
humoral factors but no decline in phosphate
Act on bone to promote resorption similar to PTH
Measured is parathyroid related protein (PTHrP)
PTHrP only elevated in hypercalcemia of malignancy
Idiopathic (especially In cats)
Exclusion diagnosis
Primary hyperPTHism rare in cats
Ca++ ranges from 10.6‐14.1 mg/dl (Mean 12.4 mg/dl)
Ionized Ca++ ranges from 5.9‐7.6 mg/dl (N=4.0‐5.5 mg/dl)
Most cats receiving an acidifying diet
Often evaluated for urinary calculi (Ca oxalate)
Change diet to non‐acidifying
Temperature