Excess Parathyroid Hormone in Cats: Vet Insights 🐱🧠 2025

By Dr Duncan Houston BVSc, veterinarian & founder of Ask A Vet.

Hyperparathyroidism in cats—a condition of excess parathyroid hormone (PTH)—may seem rare, but early understanding is vital for healthier, happier cats. This guide explores:

• 🔍 What is PTH & hyperparathyroidism?
• 🧬 Primary vs secondary causes
• 🚨 Signs to catch early
• 🧪 Diagnostic steps (lab tests, imaging)
• 💊 Treatment options (surgery, medication)
• 🍽️ Diet, home care & monitoring
• 🤝 How Ask A Vet, Woopf & Purrz help

🧠 Understanding Parathyroid Hormone (PTH)

PTH is an 84‑amino‑acid peptide hormone produced by small parathyroid glands near the thyroid. It:

• 📈 Raises blood calcium by releasing it from bones
• 🧂 Increases calcium reabsorption in kidneys
• ☀️ Boosts vitamin D activation for intestinal calcium uptake

When PTH is higher than normal—especially with high calcium—it signals hyperparathyroidism :contentReference[oaicite:2]{index=2}.

📚 Types of Hyperparathyroidism in Cats

1. Primary Hyperparathyroidism

• Usually caused by a parathyroid gland tumor (adenoma or hyperplasia)
• Leads to PTH-driven hypercalcemia → weakened bones, stones, tissue calcification :contentReference[oaicite:3]{index=3}
• Rare in cats, but serious enough to require surgery :contentReference[oaicite:4]{index=4}

2. Secondary Hyperparathyroidism

• Occurs reactive to another condition:
• 🔹 CKD: kidneys fail to excrete phosphate → low calcium → high PTH :contentReference[oaicite:5]{index=5}
• 🔹 Nutritional imbalance (low calcium / high phosphorus diets) :contentReference[oaicite:6]{index=6}
• PTH may return to normal when the underlying issue is resolved
• Tertiary hyperparathyroidism can occur if PTH becomes self-sustaining

🔎 Common Signs & Symptoms

Symptoms stem from high blood calcium (hypercalcemia) and ongoing PTH effects:

• Increased thirst & urination (PU/PD) 💧
• Poor appetite, weight loss, vomiting 🤢
• Lethargy, muscle tremors, weakness 😴
• Constipation, bloody urine, uroliths 🚽
• Bone pain, fractures, jaw deformities (fibrous osteodystrophy) :contentReference[oaicite:7]{index=7}

Some cats may be asymptomatic – diagnosis often incidental with bloodwork :contentReference[oaicite:8]{index=8}.

🧪 Diagnostic Approach

1. Blood Tests: total and ionized Ca, PTH, phosphorus, kidney values, CBC :contentReference[oaicite:9]{index=9}
2. PTH Assay: high PTH with high calcium confirms hyperparathyroidism :contentReference[oaicite:10]{index=10}
3. PTH-rP: rules out humoral hypercalcemia of malignancy :contentReference[oaicite:11]{index=11}
4. Urinalysis: USG, crystals, protein
5. Imaging: neck ultrasound for parathyroid mass; abdominal US/X-ray for stones or CKD :contentReference[oaicite:12]{index=12}
6. Advanced Imaging: CT/MRI or sestamibi scans in tricky cases :contentReference[oaicite:13]{index=13}

💉 Treatment Strategies

🏥 Primary Hyperparathyroidism

• Surgical parathyroidectomy: removal of the affected gland(s); often curative :contentReference[oaicite:14]{index=14}
• Intraoperative PTH monitoring ensures completeness :contentReference[oaicite:15]{index=15}
• Post-op care: calcium supplementation to prevent hypocalcemia :contentReference[oaicite:16]{index=16}

💊 Medical Management

• Fluids & Diuretics: saline for hypercalcemia, furosemide to enhance excretion
• Cinacalcet (calcimimetic): lowers PTH/ calcium levels when surgery isn't an option :contentReference[oaicite:17]{index=17}
• Bisphosphonates: help protect bones in chronic cases

🎯 Secondary Hyperparathyroidism

• CKD‑associated: manage kidney disease, restrict phosphorus, enhance hydration
• Nutritional: correct diet ratios; possibly use phosphate binders
• If PTH stays high → may consider surgical removal if tertiary changes occur

🏡 Home & Lifestyle Tips

• ✅ Always fresh water + encourage wet food
• ✅ Regular monitoring of urine, appetite & weight
• ✅ Smooth diet transitions with warming, palatable food
• ✅ Check litter box habits closely
• ✅ Partner with Ask A Vet for between‑visit support

📅 Follow-Up & Monitoring

Recheck labs (Ca, PTH, kidney values) every 4–8 weeks post-treatment, then every 3–6 months. Monitor urine, blood pressure, and bone health for early detection of complications.

🤝 Role of Ask A Vet, Woopf & Purrz

At Ask A Vet, we offer:

• 📱 24/7 tele-vet support for lab interpretation
• 💬 Personalized care plan check-ins
• 🍽️ Guidance on renal/nutrition foods from Woopf & Purrz, tailored to PTH and kidney health

✅ Key Takeaways

• 🔹 Monitor calcium AND PTH to confirm hyperparathyroidism
• 🔹 Distinguish primary vs secondary causes—vital for treatment
• 🔹 Surgery is curative for primary cases; medical therapy helps too
• 🔹 CKD/nutritional forms may necessitate lifelong management
• 🔹 At-home hydration, diet, and Ask A Vet support optimize outcomes

📞 Final Thoughts

Hyperparathyroidism may be rare, but properly managed cats thrive! With vet care, dietary support from Woopf & Purrz, and Ask A Vet guidance, you can ensure your kitty’s best life 😊.

For personalized support or to discuss your cat’s calcium results, visit AskAVet.com and download the Ask A Vet app today!