5-HT Archives

01 Dec 2024

23 Comments

Neuroendocrine Cancer – tumour markers and hormone levels

A Spotlight on NENs - Testing Series, Patient Advocacy131I-Metaiodobenzylguanidine (mIBG), 5-HIAA, 5-HT, 5-HTP, 5-Hydrotryptophan (5-HTP), 5-Hydroxyindoleacetic Acid (5-HIAA), 5-Hydroxytryptamine (5-HT), Adrenocorticotropic Hormone (ACTH), Biopsy, C-peptide, Calcitonin, Carcinoid crisis, Carcinoid heart disease, Carcinoid syndrome, Catecholamines, Chromaffin cells, Chromogranin, Chromogranin A (CgA), Chromogranin B (CgB), Chromogranin C (CgC), Cortisol, Electrolytes, Endocrine, Fasting Gut Endocrine Profile, Flushing, Gastric NET, Gastrin, Gastrin pH, Gastrinoma, Gastroesophageal reflux disease (GERD), Genetic testing, Glucagon, Glucagonoma, Hedinger syndrome, Histamine, Hormones, Hypertension, Insulin, Insulinoma, MEN1 syndrome, Metanephrines, Molecular markers, NETest, Neuroendocrine, Neuroendocrine cancer, Neuroendocrine carcinoma (NEC), Neuroendocrine tumour (NET), Neurokinin A (NKA), NKA, NT-proBNP, Pancreastatin, Pancreatic cancer, Pancreatic NET (PanNET), Pancreatic polypeptide (PP), Pheochromocytoma, Plasma 5HIAA, PPoma, Proinsulin, Proton pump inhibitors (PPI), Red blood count (RBC), Renal insufficiency, Serotonin, Serum serotonin, Somatostatin, Somatostatinoma, Substance K, Substance P, Tachycardia, Tachykinin, VIPoma, Wheezing, Zollinger-Ellison Syndrome

Originally published 2016, updated October 2025 Background Some people hear the terms "tumour markers" and "hormone levels" when they are diagnosed with Neuroendocrine Neoplasms (NENs). That might be confusing or even alarming at the time. Most people diagnosed with cancer will have had a form of medical testing at some point in their life, i.e. the sampling and testing of blood, urine, saliva, stool or body tissue. With NENs, the medical staff are just measuring the content of a 'substance' and then taking a view whether this is normal or not based on pre-determined ranges. These tests are normally done…

29 Aug 2024

By Ronny Allan

20 Comments

Serotonin – the NET effect

Diet and Nutrition, Living with Neuroendocrine Cancer, Patient Advocacy, The NET Effect Series5-HIAA, 5-HT, 5-HTP, 5-Hydrotryptophan (5-HTP), 5-Hydroxyindoleacetic Acid (5-HIAA), 5-Hydroxytryptamine (5-HT), Antidepressant, Anxiety, Blood brain barrier (BBB), Bradykinin, Brain serotonin, Cancer anger, Carcinoid heart disease, Carcinoid rage, Carcinoid syndrome, Depression, Desmoplasia, Diarrhea, Dopamine, Endocrine, Flushing, Foregut, Hindgut, Histamine, Hormones, Monoamine oxidase inhibitors (MAOIs), NET syndromes, Neuroendocrine, Neurotransmitter, Norepinephrine, Nutrition, Oxitriptan, Prostaglandin, Selective Serotonin Reuptake Inhibitor (SSRI), Serotonin, Serotonin and norepinephrine reuptake inhibitor (SNRI), Serotonin syndrome, Serum serotonin, St. John's wort, Thorson-Bioerck syndrome, TPH1, TPH2, Tricyclic antidepressant, Tryptophan, Tryptophan hydroxylase (TPH)

Background I'd never heard of Serotonin until I was diagnosed with Neuroendocrine Cancer in 2010. It is frequently discussed, often with contrasting views from the respondents. One common assumption/question is that it is responsible for many things that can go wrong with Neuroendocrine Tumour (NET) patients who have serotonin-producing tumours. To a certain extent, that's true but statement such as "it's the hormones" is an easy assumption to make; or an easy answer to give in response to a complex set of circumstances. It's difficult to get a definitive answer and the science behind the behaviour of our hormones isn't…

14 May 2024

By Ronny Allan

8 Comments

Neuroendocrine Cancer: Fibrosis – an unsolved mystery?

Living with Neuroendocrine Cancer, Treatment5-HT, Advanced neuroendocrine cancer, Carcinoid heart disease, Carcinoid syndrome, Carcinoid tumour, Dermal fibrosis, Desmoplasia, Hedinger syndrome, Hormones, Hydrocele, Hydronephrosis, Intestinal ischaemia, Mesentery, Neuroendocrine cancer, Neuroendocrine tumour (NET), Peritoneal carcinomatosis, Pleural Fibrosis, Pulmonary fibrosis, Retroperitoneal Fibrosis, Retroperitoneum, Scleroderma, Serotonin, SI NET, Small intestine NET (SI NET)

What happened to me? Since I was diagnosed in 2010, I've always known about a fibrosis issue in my retroperitoneal area. It was identified on the very first CT scan which triggered my diagnosis. Here's how the radiologist described it - "There is a rind of abnormal tissue surrounding the aorta extending distally from below the renal vessels. This measures up to 15mm in thickness". Followed by a statement saying that it was "almost certainly malignant". The second and third scans would go on to describe as "retroperitoneal fibrosis" and "a plaque-like substance". Interestingly the fibrosis itself does not appear…

06 Feb 2024

By Ronny Allan

0 Comments

Histamine – NET or NOT?

Patient Advocacy, The NET Effect Series5-HT, Carcinoid syndrome, Duodenal NET (dNET), Gastric NET, Gastrin, Gastrinoma, Histamine, Hypergastrinemia, Lung NETs, Pancreatic NET (PanNET)

Histamine is mentioned a lot in both patient groups and in literature as somehow connected with NETs, particularly with so called carcinoid syndrome (CS). In fact, various putative mediators, including serotonin, catecholamines, brady- and tachykinins, kallikrein, histamine, motilin, and prostaglandins, have been suggested as potential causative factors for the symptoms and complications associated with CS. It is generally believed that most of these tumour-derived secretory products are inactivated by hepatocytes and, therefore, only cause symptoms when they either bypass or are secreted outside of the portal vein drainage system. I wanted to focus on Histamine in this article. But what is the…

28 Apr 2023

By Ronny Allan

2 Comments

A spotlight on 5-HIAA

A Spotlight on NENs - Testing Series, Patient Advocacy5-HIAA, 5-HT, Carcinoid heart disease, Carcinoid syndrome, Carcinoid tumour, Diagnosis, Functional tumour, Hedinger syndrome, Neuroendocrine cancer, Neuroendocrine tumour (NET), Plasma 5HIAA, Serotonin

Background. It's important to note that not every type of Neuroendocrine Neoplasm will get the same tests due to the heterogenous nature of this cancer type. Some are more specific than others. A wide range of tests may be necessary at diagnosis if the type of NET is not clear. This post will cover one of the main tests to check for a common type of Neuroendocrine Tumour (NET) that is known to secrete excess amounts of the hormone Serotonin leading to symptoms indicative of Carcinoid Syndrome. These tumours are often labelled using the antiquated and misnomer term ‘Carcinoid Tumour’ but…

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